-1.92% is the change from 939 to 921
Calculation steps:
[( 921 - 939 ) ÷ 939] x 100 = -1.92%
Formula
Percentage change = [(921 - 939) / 939] x 100
Subtract the new number by the original number
921 - 939 = -18
-18 ÷ 939 = -0.019169329073482427
-0.019169329073482427 x 100 = -1.92%