The way to try to establish if a particular group of men, defined by whatever demographic variable you wish to look at (race, ethnicity, religion, age, class, cultural values) is over-represented in mass grooming would be to ask if men from all the different demographic groups groom girls at the same percentages, or if some groups show higher percentages.
Because in the UK white men are the majority of men, it would be extremely unlikely not to find that they would also be the numerical majority of the groomers, even if white men were no more likely to groom than other men, and even if they were less likely to groom than other men.
So absolute numbers are not that informative, because even if, say, 2% of all the different groups of men groomed young girls, there would be lots more cases where white men were found to do the grooming because there are so many more white men.
This means that we should look at percentages of men who do grooming out of the size of each sub-population of men. Are those percentages the same? Do some sub-populations show much higher percentages, and if this is the case, what is the reason?
There's not complete data on this, because not all cases (or perhaps even most cases) have come to the attention of the police and also because the police may arrest men from different demographic groups at different rates (for many reasons, including political power of the possible culprits, racism by the police, tribal identification by the police etc.).
So what we have is data on cases which have come to the attention of the police, which we should gather and analyse while keeping in mind its limitations.
As to the Rochdale case, I read the reports on it some years ago, and it was clear from those reports that in that community the grooming gangs largely consisted of men of Pakistani origin. The situation elsewhere might well be different.
One comment made by someone in the report (or other material I read at the time) was that certain industries (takeaways, taxi services) lend themselves more to 'mass' grooming as the work takes place often late at night, taxi drivers develop networks of possible clients, takeaways can be used for organising etc. And at Rochdale these industries had predominantly Pakistani workers and owners.
But nobody suggested this as the main reason.
The report addressed the sexism of the police. Some officers viewed the young girls as simply prostitutes and didn't respond to their complaints, because they didn't view them as children in need of safeguarding.
There were also problems with the social work system. Some of the victims lived in care homes where the girls would be picked up after school by the groomers. These were particularly vulnerable children who were let down by the system.
I also recall being concerned with the way the police or local politicians, when addressing the problems, decided to communicate only with what they viewed as leaders of the local Muslim communities (as if we had two different countries or something similar to that, and as if the men they viewed as leaders of the 'other' country somehow could speak for all its 'citizens'). This kept all the Muslim women and girls unheard by the police, as one example of why I felt concern, so we may never have heard about them being groomed if that happened.