100% by definition is the maximum of the percentile scale, cent=100, not 110 or 300, just 100, so reachng 100 in the percentile scale means you have 100%, full up, cant get no more in. Unless your the makers of pepperami which has 115% meat products, meaning they fill it wi meat (100%), then cram a bit more in (115%)
It is a stupid, nonsensical turn of phrase coined and repeated by pillocks. And if your doing something in 20seconds one day then you do it in 18 the next does not mean your giving 110%, you have just increased the amount you can do before you reach 100% and max out (or you werent trying hard enough before). Come on people, pull your fingers out and use 100% of your grey matter.