NEW YORK (AP) — Philanthropists Bill and Melinda Gates pitched an optimistic future for the world's poor and sick in their annual letter Tuesday, arguing passionately against three myths they say hurt efforts to bring people out of poverty, save lives and improve living conditions. In their sixth yearly letter, which in the past has focused exclusively on the Bill & Melinda Gates Foundation's annual activities, the co-chairmen of the world's largest charitable foundation seek to dispel notions that poor countries are doomed to stay poor, that foreign aid is wasteful and that saving lives will cause overpopulation. "All three reflect a dim view of the future, one that says the world isn't improving but staying poor and sick, and getting overcrowded," Bill Gates writes in the 16-page letter. "We're going to make the opposite case, that the world is getting better, and that in two decades it will be better still." Gates says GDP per capita figures, adjusted for inflation to 2005 dollars, show that many countries such as China, India, Brazil and even Botswana that were once considered poor now have growing economies. And in Africa, a place the Microsoft co-founder says is all too often dismissed as hopeless, life expectancy has risen since the 1960s despite the HIV epidemic.