I guess the issue we're seeing is that even then it isn't a consistent 10% across the country. In some areas it may be 1%, in other more like 20%. And then you get people travelling to join the planned trouble also.
Clearly hotspots - and it's not a surprise that it's the poorer towns that are the focus.
Even then, most of the "riots" seem to be a few hundred people at most, and probably just a few dozen actively participating in rioting. Even in Middlesborough or Hartlepool, I expect it's not 1% of the actual population out causing trouble.