Bluenose,
You're absolutely right to say that
they actually mean "23% of UK (Military) SAR (Helicopter) callouts are coastal"
but, as Crab points out, adding in the MCA stats wouldn't make much difference - pushing the coastal total up to 30-35% or so (at a guess) doesn't change my point.
I disagree that we should describe SAR as a coastal rescue business just because
Most of the UK SAR helicopters bases are located on the coast
Surely one could argue that the bases are on/near the coast to be a compromise between all the maritime jobs and all the land jobs! Your logic would conclude that nuclear power stations chiefly supply electricity to remote communities just because they happen to be in the middle of nowhere!