Developing nations will account for a vast and growing majority of the global population in 2050, while industrial countries will stay about the same size, UN demographers reported on Tuesday. The world's population, which stood at 6.1 billion in mid-2000, will likely reach 9.3 billion in 2050, although it could be as high as 10.9 billion or as low as 7.9 billion, the UN Population Division said in its latest update of World Population Prospects.