Mr.jamshi naju, the percentage may be an exaggeration but there are good number of criminals (hope you are aware of Calicut Ice Cream parlour case in which one of the accused was Mr. P.K. Kunhali Kutty - the victim was also a muslim girl).
No religion has ever stopped people from committing crimes. There are any number of cases against prominent members of priestly class from all religions.
When the religiosity is insufficient to curtail such activities, what is the use of them?