Wow - more than 50% in the past 4 years is a very steep drop in participation, steeper than the typical "youth rec sports participation is decreasing" articles I've read recently (see attached image). I wonder if your area is missing kids in general -- birth rates dropped pretty quickly during the recession of 2008-2010 and haven't recovered. This drop may be starting to affect rec sports (and school enrollment) now? I've linked a fairly recent article from the local paper near me.