My parents fly around 2 R/T EWR-HKG a year since the route started about 10 years ago. So, say about 40 flights each. Minus about 12-14 that they were actually booked on BF, but add about 12-14 other non-HKG longhauls in coach.

My mom has gotten op-uped once for HKG due to coach overbooking. My dad also got op-uped once, but that was right after 9/11 and the whole flight was basically empty. So, about 2.5% each. That's in-line with star_world's 2% number.