-0.15% is the change from 667 to 666
Calculation steps:
[( 666 - 667 ) ÷ 667] x 100 = -0.15%
Formula
Percentage change = [(666 - 667) / 667] x 100
Subtract the new number by the original number
666 - 667 = -1
-1 ÷ 667 = -0.0014992503748125937
-0.0014992503748125937 x 100 = -0.15%