China’s demographic transition is perhaps the clearest example of the global trend. The world population soared in the twentieth century, growing from 1.6 billion in 1900 to about 6 billion in 2000. Now, forecasters predict that the majority of the world except for some countries in sub-Saharan Africa will experience Population decline by the end of the century. The United States, like China too Saw the slowest population Growth in nearly a century over the past decade. According to research published last year in scalpel, a British medical journal, states 23 countries, including Japan and Italy, whose populations will be halved by 2100.