-2.5% is the change from 681 to 664
Calculation steps:
[( 664 - 681 ) ÷ 681] x 100 = -2.5%
Formula
Percentage change = [(664 - 681) / 681] x 100
Subtract the new number by the original number
664 - 681 = -17
-17 ÷ 681 = -0.024963289280469897
-0.024963289280469897 x 100 = -2.5%