Without resorting to handpicked and sorted stats it's obvious GA is only a small percentage of what it used to be. In the bush you are lucky to see any sign aircraft of any sort apart from vapour trails. It's gone from every town airstrip having training and charter, most farmers having 182's and thriving maintenance shops to barren rural airstrips. RAA is the only hope but CASA is working to destroy that too.
With GA being a small percentage of what once was then it stands to reason any events will correspondingly be down the same percentage. Then you have event organisers thinking they will cash in compounding the non participation.
GA exists in spite of CASA not because of it.