3.37% is the change from 504 to 521
Calculation steps:
[( 521 - 504 ) ÷ 504] x 100 = 3.37%
Formula
Percentage change = [(521 - 504) / 504] x 100
Subtract the new number by the original number
521 - 504 = 17
17 ÷ 504 = 0.03373015873015873
0.03373015873015873 x 100 = 3.37%