-18.38% is the change from 816 to 666
Calculation steps:
[( 666 - 816 ) ÷ 816] x 100 = -18.38%
Formula
Percentage change = [(666 - 816) / 816] x 100
Subtract the new number by the original number
666 - 816 = -150
-150 ÷ 816 = -0.18382352941176472
-0.18382352941176472 x 100 = -18.38%