81.55% is the change from 309 to 561
Calculation steps:
[( 561 - 309 ) ÷ 309] x 100 = 81.55%
Formula
Percentage change = [(561 - 309) / 309] x 100
Subtract the new number by the original number
561 - 309 = 252
252 ÷ 309 = 0.8155339805825242
0.8155339805825242 x 100 = 81.55%