-40.3% is the change from 990 to 591
Calculation steps:
[( 591 - 990 ) ÷ 990] x 100 = -40.3%
Formula
Percentage change = [(591 - 990) / 990] x 100
Subtract the new number by the original number
591 - 990 = -399
-399 ÷ 990 = -0.403030303030303
-0.403030303030303 x 100 = -40.3%