19.78% is the change from 91 to 109
Calculation steps:
[( 109 - 91 ) ÷ 91] x 100 = 19.78%
Formula
Percentage change = [(109 - 91) / 91] x 100
Subtract the new number by the original number
109 - 91 = 18
18 ÷ 91 = 0.1978021978021978
0.1978021978021978 x 100 = 19.78%