-2.51% is the change from 678 to 661
Calculation steps:
[( 661 - 678 ) ÷ 678] x 100 = -2.51%
Formula
Percentage change = [(661 - 678) / 678] x 100
Subtract the new number by the original number
661 - 678 = -17
-17 ÷ 678 = -0.025073746312684365
-0.025073746312684365 x 100 = -2.51%