-2.92% is the change from 686 to 666
Calculation steps:
[( 666 - 686 ) ÷ 686] x 100 = -2.92%
Formula
Percentage change = [(666 - 686) / 686] x 100
Subtract the new number by the original number
666 - 686 = -20
-20 ÷ 686 = -0.029154518950437316
-0.029154518950437316 x 100 = -2.92%