Billionaire philanthropist Warren Buffett donated $30 billion to the Bill and Melinda Gates Foundation in 2006. Buffett recently wrote a letter to the Gates, requesting they update the world as to all the foundation had accomplished in tackling global poverty.

The Gates responded with a letter of their own.

“Of course, philanthropy isn’t like business,” the letter states. “We don’t have sales profits to show you. There’s no share price to report. But there are numbers we watch closely to guide our work and measure our progress.”

These are those numbers:

122 million children’s lives saved since 1990

Bill reports, “More children survived in 2015 than in 2014. More survived in 2014 than in 2013, and so on. If you add it all up, 122 million children under age five have been saved over the past 25 years.”

That figure is arrived at by looking at the mortality rate of children under age five in developing countries and comparing the trend line in 1990 and 2000 to the rate it’s currently at.

5.9 million children under age five died in 2015, according to the United Nations. Still, thanks to the Gates Foundation and help from donors like Buffett, that rate has fallen sharply – and continues to drop each year.

It is difficult to describe the feeling of improvement within tragedy. As Melinda said, “Every year, this number breaks my heart and gives me hope.”

86% of children worldwide have been vaccinated

That rate is the highest in human history and one of the main factors for the declining childhood mortality rate.

According to the World Health Organization, vaccination is the second-most effective method to reduce disease, behind access to clean water. Smallpox is the only disease to be eradicated thus far, but polio is on the ropes and the Gates Foundation has recently refocused global efforts to end malaria for good.  

Vaccination has a snowball effect in helping families. According to the letter, in addition to the health of the child, every dollar spent on childhood immunizations saves $44 – money that would be spent/lost later when the child is ill and parents miss work.

The Gates Foundation also helped establish Gavi, the Vaccine Alliance, which works with governments and businesses to develop vaccines and distribute them to people in need. With funding from the world’s wealthier governments, like the US, UK, Norway, Germany, France, and Canada, Gavi has been instrumental in immunizing 580 million children worldwide.

Read More:Gavi Pledges to Reach Syrian Children With Lifesaving Vaccines

1 million infants died on the day they were born

But there is hope. Even in poorer nations like Rwanda, there have been drastic improvements in lowering the infant mortality rate.

The letter states, “From 2008 through 2015, Rwanda, one of the poorest countries in Africa, cut its newborn mortality by 30 percent.”

The drop wasn’t exactly a scientific breakthrough. A combination of breastfeeding in the first hour of life and exclusively for the first six months, cutting umbilical cords properly and in sanitary conditions, and kangaroo care (mother’s holding newborns against their skin, proven to help stabilize heart rate, increase body temperature and improve brain development) have had overwhelmingly positive results.   

Nevertheless, much is still unknown about the causes of asphyxia, sepsis, and premature deaths (responsible for more than two-thirds of infant deaths in the first month of life). The Gates Foundations will lead research efforts to gain that knowledge and develop treatments.   

45% of deaths of children under 5 are linked to malnutrition

Not to be confused with starvation, people who are malnourished may be taking in enough calories to sustain life, but are not getting the right nutrients. As a result, they are more vulnerable to (potentially fatal) bouts of pneumonia and diarrhea.

According to the World Food Programme, 795 million people – majority of them in developing countries – lack enough food to be deemed healthy. Poor nutrition causes 3.1 million deaths each year in children under the age of 5.     

300 million women in the developing world are using modern contraceptives

“When women in developing countries space their births by at least three years, their babies are almost twice as likely to reach their first birthday,” the letter states. “Over time, the ability of women to use contraceptives and space their pregnancies will become one of the largest contributors in cutting childhood deaths.”

Much like vaccines having long-term benefits, when women can plan pregnancies, they have greater access to education. This helps them establish incomes which, in turn, allows them to raise healthier children.

Again, Melinda nails it: “No country in the last 50 years has emerged from poverty without expanding access to contraceptives.”

Read More:Millions of Lives at Risk With Global Gag Rule, Bill and Melinda Gates Say

75 million women are in self-help groups in India

Poorer societies tend to be the ones in which women are the most powerless. Solidarity is the solution.

Among social efforts, the Gates Foundation has worked to, “create community groups in India where sex workers had a place to go and talk about HIV protection.”

Modern contraceptives are a huge part (see: the previous section).

Knowledge is power. In societies that overtly limit women’s abilities, discussions and sharing wisdom can be a key to social advancement.

1% of people surveyed knew that extreme poverty has been cut in half since 1990

The world is not nearly optimistic enough in its fight to eliminate extreme poverty worldwide.

The letter claims that, though extreme poverty had been halved worldwide, many people believed poverty was actually increasing.

“In significant ways, the world is a better place to live than it has ever been. Global poverty is going down, childhood deaths are dropping, literacy is rising, the status of women and minorities around the world is improving.”

We still have a way to go, however. Global Citizen is committed to ending extreme poverty by 2030 – but it’s going to take collective action from Global Citizens across the world. Believing the goal is achievable is step one.  

Read More:UK Scientists Just Made a Major Breakthrough With the Polio Vaccine

0 – the magic number

Fans of the hip-hop group De La Soul might say three is the magic number. Well, they’d be wrong – it’s zero.  

That means, “Zero malaria. Zero TB. Zero HIV. Zero malnutrition. Zero preventable deaths. Zero difference between the health of a poor kid and every other kid.”

It seems like a hefty goal, but, as the letter states, we’re almost there with polio. The disease has proven to be resilient in countries like Nigeria, India, Pakistan, and Afghanistan, but it’s 99% eradicated worldwide. When it is finally gone for good, efforts can be refocused elsewhere.

It will take time, devotion, and cooperation between individuals, businesses, and governments, not to mention fundraising from people like Buffett. But the value from helping another human being in need cannot be quantified.    

“That’s the magic of philanthropy,” Melinda said in the letter. “It doesn’t need a financial return, so it can do things business can’t. But the limit of philanthropy is that the money runs out before the need is met. That’s why business and government have to play a role if the change is going to last.”

Disclosure: The Bill and Melinda Gates Foundation is a funding partner of Global Citizen.

Editor's note: This piece has been updated to include a disclosure that the Bill and Melinda Gates Foundation is a funding partner of Global Citizen. We regret the oversight.