That Medium article is completely misleading, their compiled "list" of White British grooming gangs has some on there that are no more than one individual in more than one instance.
They also used a disgusting picture which implicitly used the same form of imagery as grooming gang suspects. This same photograph was distributed by "Militant Antifa" hardly a non-partisan article is it? It then named this group their own "gang" in some disgusting joke.
Then there is another graph which shows White Britons slightly higher group perpetrators. This is unsurprising, given the former population is 87% according to the 2011 census. This same graph shows the "Asian" as close to outstripping whites, which suggests their proportion is very higher given relative to their population size.