I'm not sure what was meant by "between 1960 and 1960", so I'll assume you mean the period 1960-70. A tripling in a decade for the behavior of a fairly stable p

I'm not sure what was meant by "between 1960 and 1960", so I'll assume you mean the period 1960-70. A tripling in a decade for the behavior of a fairly stable population can't be real, so this was probably more closely related to effort devoted to policing, changes in classification policy, etc. If you linked to something we could consider it.