Jesus was born in 4 BC (more or less) and live to be 33 years old, which means His death was around 29 AD (more or less). That was precisely, 1992 years ago
An increase of 2% per year means the population is multiplied by 1.02 each year. Your exponential function with a base of 1.02 and a scale factor of 5.3 (billion) will look like this:
