We sometimes use percentages greater than 100, but they do not generally help the reader, unless we are quoting a footballer who says he “gave it 110 per cent”.
We had this headline on Thursday: “Popular London outdoor swimming spot sees 1,188 per cent increase in bacteria.” We might as well have said “a huge increase” because no one knows how much 1,188 per cent is. Having thought about it and checked my arithmetic, it is more than a twelvefold increase. We could have said that.
