Because, as justizin and dragonwriter [1] explained above, the actual SWAT team members are employees of the police.
I would assume you could query each individual agency as to how often their officers participate in swat operations, but without knowing how often the LEC was called, I don't see how you could get an accurate count of the total raids. Perhaps each jurisdiction would have to report how often they called the LEC into their jurisdiction.
They may be actually be legally right due to basically a technicality. Perfect for time for the state legislature to reign in the LECs and make open records apply to mutual aid agencies/agreements. I'm sure their representatives are jumping on that right now...