Hmmm .... if you don't have a record of what flights you took to earn that number of points, are you sure you spent less than $8,500 in total? If you earned 170,000 QFF points on a spend of less than $8,500, that would make your average earn rate more than 20 points per dollar. However, if you pay $100 for a QF domestic flight with the 1,000 point guarantee, your earn rate is just half that - 10 points per dollar (and exactly the same as a Platinum on VA, funnily enough). I don't believe you can average much better than 10 points per dollar on the 1,000 pt guarantee flights (but as illustrated above, you can do a lot worse - I'd say my average is about 5 points per dollar spent with QF on MEL-SYD flights).

So to have an average earn rate of 20 points per dollar across all your QF flying, your international flights would have had to earn significantly more than 20 points per dollar - possibly even 30 points per dollar or more. How is that possible? SYD-SIN-SYD (for example) earns a QF WP about 7,800 QFF points under the current (old) rules, so the fare would have to be just $390 return for the earn rate to be 20 points per dollar, or $260 return for the earn rate to be 30 points per dollar. In reality, a sale fare is currently about $750, which funnily enough also corresponds to an earn rate of about 10 points per dollar.

So if you managed to average 20 points per dollar spent with QF, I think there must have been something very unusual about your flying pattern, and/or you made heavy use of MASAs?