-21.5% is the change from 814 to 639
Calculation steps:
[( 639 - 814 ) ÷ 814] x 100 = -21.5%
Formula
Percentage change = [(639 - 814) / 814] x 100
Subtract the new number by the original number
639 - 814 = -175
-175 ÷ 814 = -0.214987714987715
-0.214987714987715 x 100 = -21.5%