As snowy Davos becomes engulfed in the hustle and bustle of another World Economic Forum, Microsoft founder Bill Gates took the opportunity to deliver an upbeat message in his annual newsletter. The 25-page report, written by Gates and his wife Melinda, who are co-chairs of the Bill & Melinda Gates Foundation, argued that the world is a better place than it has even been before. Gates predicted that by 2035, there would be almost no poor countries left in the world, using today's World Bank classification of low-income countries — even after adjusting for inflation. "Poor countries are not doomed to stay poor. Some of the so-called developing nations have already developed," he said in a his annual note, published on Tuesday.

"I am optimistic enough about this that I am willing to make a prediction. By 2035, there will be almost no poor countries left in the world." (Read More: In Davos, stern challenge for the rich)

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Gates — who remains a part-time chairman of Microsoft — added that by this point in time, almost all countries will be "lower-middle income" or richer. Countries will learn from their most productive neighbors and benefit from innovations like new vaccines, better seeds, and the digital revolution, he said. "By almost any measure, the world is better than it has ever been. People are living longer, healthier lives. Extreme poverty rates have been cut in half in the past 25 years. Child mortality is plunging. Many nations that were aid recipients are now self-sufficient," he said. Three big myths Back for another year at Davos, Gates will take the stage on Friday to address myths about global development, and will challenge its most vocal critics. (Read More: The rich and famous visit Davos) The three biggest myths, according to Gates, are that poor countries are doomed to stay poor, that foreign aid is a big waste and that saving lives leads to overpopulation. Using data from academics, the World Bank and the United Nations, he makes the opposite case — arguing that the world is getting better.

"I understand why people might hold these negative views. This is what they see in the news. Bad news happens in dramatic events that are easy for reporters to cover," he said. "Countries are getting richer, but it's hard to capture that on video. Health is improving, but there's no press conference for children who did not die of malaria." (Read More: Don't trust the government? You're not alone)

According to the World Bank's preliminary estimates, the extreme poverty rate was halved between 1990 and 2010. This meant that 21 percent of people in the developing world lived on or below $1.25 a day, down from 43 percent in 1990 and 52 percent in 1981. The World Bank last year set a goal of decreasing the global extreme poverty rate to no more than 3 percent by 2030.

Bill Gates is no stranger to the World Economic Forum. At last year's event, he outlined his concerns that austerity measures could hit public funding for deadly diseases like malaria, tuberculosis and HIV. "The money that helps out the poorest overwhelmingly comes from government aid budgets", Gates told CNBC at last year's Davos, adding that it was unclear what kind of priority aid will have in future budgets.