-18.31% is the change from 661 to 540
Calculation steps:
[( 540 - 661 ) ÷ 661] x 100 = -18.31%
Formula
Percentage change = [(540 - 661) / 661] x 100
Subtract the new number by the original number
540 - 661 = -121
-121 ÷ 661 = -0.18305597579425115
-0.18305597579425115 x 100 = -18.31%