For those of you who use your miles for International F and J tickets, how many miles do you normally accumulate in a year? Also what percentage of those miles come from something other than actual miles flown?

I will b flying about 4-5 Tran-Pacific r/t and some domestic flights back in the US next year. That seems like a lot to me but at that rate it will be years before I can afford to purchase an international F class ticket with only miles. Am I missing something or do I just not fly as much as I feel that I do.