-99.4% is the change from 671 to 4
Calculation steps:
[( 4 - 671 ) ÷ 671] x 100 = -99.4%
Formula
Percentage change = [(4 - 671) / 671] x 100
Subtract the new number by the original number
4 - 671 = -667
-667 ÷ 671 = -0.9940387481371088
-0.9940387481371088 x 100 = -99.4%