Now, in fairness, he has a right (and a responsibility) to defend his city, but I take issue with this.
Google searches:
stabbed London 1,690,000 results
stabbed Rome 692,000 results
stabbing London 1,310,000 results
stabbing Rome 656,000 results
population London 13,063,441 (metro area - it's about 7.5M for the city)
population Rome 2,724,347
I'd also like to point out that "stabbing" and "stabbed" are English words.
What I'm getting at here is that the stat quoted by the Mayor of Rome is (a) wrong and (b) retarded as a measure of anything anyway.
EDIT:
This site gives crime figures for London. Anyone able to find an equivalent site for Rome? I have no Italian to go looking.