-18.28% is the change from 815 to 666
Calculation steps:
[( 666 - 815 ) ÷ 815] x 100 = -18.28%
Formula
Percentage change = [(666 - 815) / 815] x 100
Subtract the new number by the original number
666 - 815 = -149
-149 ÷ 815 = -0.18282208588957055
-0.18282208588957055 x 100 = -18.28%