I am just under 40% and get 1-2 a month. I put a lot of qualifiers in so when it doesn't get bought I am not stuck flying a POS trip.

Just because OE is assigned to the trip doesn't mean it will happen. I have had 3 trips where the new hire that is supposed to get OE busted a sim ride which clears their OE schedule automatically. So when you see OE on the trip don't make plans just yet.