-3.54% is the change from 509 to 491
Calculation steps:
[( 491 - 509 ) ÷ 509] x 100 = -3.54%
Formula
Percentage change = [(491 - 509) / 509] x 100
Subtract the new number by the original number
491 - 509 = -18
-18 ÷ 509 = -0.03536345776031434
-0.03536345776031434 x 100 = -3.54%