And any idea statistically how many concurrent callouts are there in areas where they have a police heli and helimed?
Very few if any. Police Helicopters only get called if the local helimeds are unavailable.
Also see
PAOM Part 1
Section 5, chapter 2 page 1 for the rules, which seem somewhat contradictory but are what we have to work with. It may explain why some of us are reluctant to carry out casevac when it is NOT to safe life!