6.91% is the change from 521 to 557
Calculation steps:
[( 557 - 521 ) ÷ 521] x 100 = 6.91%
Formula
Percentage change = [(557 - 521) / 521] x 100
Subtract the new number by the original number
557 - 521 = 36
36 ÷ 521 = 0.0690978886756238
0.0690978886756238 x 100 = 6.91%