-77.7% is the change from 991 to 221
Calculation steps:
[( 221 - 991 ) ÷ 991] x 100 = -77.7%
Formula
Percentage change = [(221 - 991) / 991] x 100
Subtract the new number by the original number
221 - 991 = -770
-770 ÷ 991 = -0.7769929364278506
-0.7769929364278506 x 100 = -77.7%