-0.39% is the change from 511 to 509
Calculation steps:
[( 509 - 511 ) ÷ 511] x 100 = -0.39%
Formula
Percentage change = [(509 - 511) / 511] x 100
Subtract the new number by the original number
509 - 511 = -2
-2 ÷ 511 = -0.003913894324853229
-0.003913894324853229 x 100 = -0.39%