-30.47% is the change from 919 to 639
Calculation steps:
[( 639 - 919 ) ÷ 919] x 100 = -30.47%
Formula
Percentage change = [(639 - 919) / 919] x 100
Subtract the new number by the original number
639 - 919 = -280
-280 ÷ 919 = -0.30467899891186073
-0.30467899891186073 x 100 = -30.47%