percentage increase

First, find the amount of increase:    21,200,000 - 3,100,000  =  18,100,000

Next, compare that to what you started with by dividing the amount of increase by the original number:

                                   18,100,000 ÷ 3,100,000  =  5.84 (approximately)

Finally, change that decimal answer into a percentage answer by multiplying by 100:

                                              5.84 x 100  =  584%  (approximately)