@David, Moderator posted:
It is in the Oxford English Dictionary, but with a hyphen: "percentage-wise."
As a percentage; as regards percentages; (more generally) relatively.1912 F. Soddy Matter & Energy ii. 53 Quite a large number of commonly occurring compounds had been analysed by chemists and the composition expressed percentage-wise as above.1960 Guardian 8 Mar. 1/2 The number of deaths percentagewise is far less than other deaths..by other heating means.1991 N.Y. Times 8 Oct. b11/4 Harper threw out only 28 of 126 potential base-stealers this season, the worst record percentage-wise in the league.
Most dictionaries show it with a hyphen. Except for this one:
I'm worried since I intend to use it on my IELTS.