2.56% is the change from 508 to 521
Calculation steps:
[( 521 - 508 ) ÷ 508] x 100 = 2.56%
Formula
Percentage change = [(521 - 508) / 508] x 100
Subtract the new number by the original number
521 - 508 = 13
13 ÷ 508 = 0.025590551181102362
0.025590551181102362 x 100 = 2.56%