68.28% is the change from 309 to 520
Calculation steps:
[( 520 - 309 ) ÷ 309] x 100 = 68.28%
Formula
Percentage change = [(520 - 309) / 309] x 100
Subtract the new number by the original number
520 - 309 = 211
211 ÷ 309 = 0.6828478964401294
0.6828478964401294 x 100 = 68.28%