What has the world’s population been over time?

Year	Population
0	200 million
1000	275 million
1500	450 million
1750	700 million
1850	1.2 billion
1900	1.6 billion
1950	2.6 billion
1960	3 billion
1975	4 billion
1985	4.85 billion
1990	5.3 billion
1999	6 billion