10.1% is the change from 99 to 109
Calculation steps:
[( 109 - 99 ) ÷ 99] x 100 = 10.1%
Formula
Percentage change = [(109 - 99) / 99] x 100
Subtract the new number by the original number
109 - 99 = 10
10 ÷ 99 = 0.10101010101010101
0.10101010101010101 x 100 = 10.1%