American Airlines shares extensive information about their frequent flyer program in their SEC filings. So their 10-K always makes for an interesting read — especially when comparing data that can be found in prior year filings.
2015 had another jump in miles issued, and at the same time a decrease in the percentage of miles sold to partners. Doing the math, the number of miles sold to partners stayed about the same (actually increased by about 1.6 billion or one-third of one percent).
The increase, then, came from miles printed by the program for travel on American. This gives us a window into the increased miles stemming from American’s premium cabin bonus.