Populating the Earth - contagian

1927 - 2,000,000,000
33 years later  -  (1960) 3,000,000,000
14 years later - (1974)  4,000,000,000
13 years later  -  (1987) 5,000,000,000
12 years later  - (1999) 6,000,000,000
12 years later - (2011)  7,000,000,000
Current is 7,632,000,000

Clear to see that the Population in over 100 years has exploded (more than doubled)??

Why??   - food, health and governance.  Is it too many or when will it be considered too many??