3.38% is the change from 503 to 520
Calculation steps:
[( 520 - 503 ) ÷ 503] x 100 = 3.38%
Formula
Percentage change = [(520 - 503) / 503] x 100
Subtract the new number by the original number
520 - 503 = 17
17 ÷ 503 = 0.033797216699801194
0.033797216699801194 x 100 = 3.38%