trying find out how many years it will take for the population of my state to double

To find out how long it takes an amount to double, you can use this formula:  t  =  ln(2) / r

where  t = time  and  r = rate (written as a decimal).

For example, if you want to know how many years that it takes a population of 22,350,000 to double if the yearly population rate increase is 9%, use:  t  =  ln(2) / 0.09   --->   t = 7.7 years (approximately).

The beginning population is not used in the calculation.