If we can extrapolate from the numbers at [1] (not sure how representative it is) then about 29% of the 233,000 total petitions would be filed under the Master's cap. That'd be around 67,337 Master's cap petitions.

[1] http://redbus2us.com/trackers/h1b-visa-tracker/

It guess this mostly matters for people who meant to apply through the Master's cap (graduates of US colleges with Master's degrees). Since there were more than 20k (as USCIS stated), the rest are reduced to regular applicants.

But it's not like they're "taking your spot" in the lottery; if there was no preferential treatment for Master's, they'd still apply as regular applicants.

I'm curious too. Also it wasn't clear what the number was last year.