Bill Gates, the world's richest man, and his wife Melinda said that conditions for the world's poorest people will improve more dramatically in the coming 15 years than at any other time in history.

Advancements in medical care and illness prevention for children, efforts to eradicate polio and other diseases and new farming techniques in Africa will drive "major breakthroughs" for most people in poor countries, according to the Bill & Melinda Gates Foundation annual letter published Wednesday night in Seattle.

Bill Gates, co-founder of Microsoft Corp., the world's largest software maker, formed the foundation in 2000 with Melinda Gates. The charity focuses on poverty and health in developing countries and education and equal opportunity in the U.S. It had given $31.6 billion in grants as of Sept. 30, according to its website.

The poor "will be living longer and in better health," according to the letter. "They will have unprecedented opportunities to get an education, eat nutritious food, and benefit from mobile banking. These breakthroughs will be driven by innovation in technology — ranging from new vaccines and hardier crops to much cheaper smartphones and tablets — and by innovations that help deliver those things to more people."

Mobile banking will make financial services more accessible, giving the poor more control over their assets, according to the letter. By 2030, about 2 billion people currently without a bank account will use their phones to make payments and store money, the Gateses wrote.

'Trickle Up'

The demand for banking in poor countries is leading to innovation that will "trickle up" to developed nations and may help overcome obstacles tied to regulations and the lack of locations to convert digital assets to paper currency, they wrote.

"We're seeing that people care about these issues, and our ability to communicate and draw people in is better than ever before," Bill Gates said in an interview with Bloomberg Television's Erik Schatzker that was broadcast today in New York. "Without the science, we couldn't make the better seeds or the vaccines. Without the donor generosity, actually getting these things out to those who need them the most, it just wouldn't happen, there's no market mechanism."

Gates's Wealth

Gates, 59, owns a fortune valued at more than $85 billion, according to the Bloomberg Billionaires Index. Microsoft's chief executive officer from 1981 to 2000, Gates stepped down as chairman last year and is a board member and technology adviser.

Warren Buffett, the second-richest man in the U.S. and a foundation trustee, has given about $15.1 billion of stock in his Berkshire Hathaway Inc., including a record $2.1 billion last year. Buffett pledged in 2006 to donate shares to the foundation every year. Bill Gates has been a Berkshire director since 2005.

Bill and Melinda Gates, along with Buffett, helped found the Giving Pledge, which asks billionaires to give the bulk of their wealth to charity. More than 120 have committed, including Facebook Inc. CEO Mark Zuckerberg and Tesla Motors Inc. founder Elon Musk.

Bill Gates predicted in the previous annual letter that by 2035 almost no country will be as poor as the 35 nations the World Bank classified as low-income as of 2014. He and Melinda Gates sought to puncture what they called myths about poverty, including the ideas that foreign aid is a waste and that saving lives leads to overpopulation.