You totally missed the point. Yes AS is a 2014 movie, and it will be counted as a 2014 movie ala GOTG, MJ1, Unbroken, etc... But if you look at the 2015 total box office #, any 2014 movie (including AS) that has made money since January 1,2015 will be counted in the 2015 domestic gross. Clearly $716M listed in the 2015 yearly gross didn't come from the movies that opened in 2015 alone.
From BOM yearly box office:
Total Gross is the calendar gross for that year, meaning actual revenues during the time period, including holdovers from previous year. For a full discussion of calendar grosses, see our page:About Box Office Tracking.