71.84% is the change from 309 to 531
Calculation steps:
[( 531 - 309 ) ÷ 309] x 100 = 71.84%
Formula
Percentage change = [(531 - 309) / 309] x 100
Subtract the new number by the original number
531 - 309 = 222
222 ÷ 309 = 0.7184466019417476
0.7184466019417476 x 100 = 71.84%