-33.92% is the change from 967 to 639
Calculation steps:
[( 639 - 967 ) ÷ 967] x 100 = -33.92%
Formula
Percentage change = [(639 - 967) / 967] x 100
Subtract the new number by the original number
639 - 967 = -328
-328 ÷ 967 = -0.3391933815925543
-0.3391933815925543 x 100 = -33.92%