-0.2% is the change from 511 to 510
Calculation steps:
[( 510 - 511 ) ÷ 511] x 100 = -0.2%
Formula
Percentage change = [(510 - 511) / 511] x 100
Subtract the new number by the original number
510 - 511 = -1
-1 ÷ 511 = -0.0019569471624266144
-0.0019569471624266144 x 100 = -0.2%