-99.9% is the change from 993 to 1
Calculation steps:
[( 1 - 993 ) ÷ 993] x 100 = -99.9%
Formula
Percentage change = [(1 - 993) / 993] x 100
Subtract the new number by the original number
1 - 993 = -992
-992 ÷ 993 = -0.998992950654582
-0.998992950654582 x 100 = -99.9%