Every year, the N.F.L. becomes more passer friendly, in quantity and quality. That trend held true in 2015, which will go down as the greatest passing season in league history.

First, a look at quantity. N.F.L. teams averaged 35.7 pass attempts per game, breaking the record of 35.4 set in 2013. Teams also set per-game records for completions (22.5) and passing yards (243.8). Passing touchdowns per game were also at a high. The record had been 1.63 a game, set, remarkably, in 1948. The league had been inching toward that mark — teams averaged 1.57 and 1.58 in 2013 and 2014 — before surpassing it with 1.64 in 2015.

For the first time, 12 quarterbacks threw for 4,000 yards. In addition, 11 threw at least 30 touchdown passes, breaking the record of nine set last season. Before 2014, no N.F.L. season had more than five quarterbacks with at least 30 touchdown throws.