Seeking Japanese Battle Festa Information!

I was wondering what sort of attendance numbers the battle festa events in Japan pull?

How many attend? How many of the promo cards roughly are given out? Are we talking 10k-20k? 25-50k? I have next to no idea how popular these Battle Festa events are and it would be cool to find some solid information about rough attendance figures.

All i see is once a year the market seems to explode with brilliant full art pikachu cards :tada: