Answered December 31st, 2017

With 72.0% on the season, Drew Brees breaks the record for highest comp % in a single season set by Sam Bradford last year.

Brees has 3 of the 4 top seasons in completion percentages in NFL history.

Highest comp % by a QB in a season
Interpreted as:
Highest comp% with a minimum of 14 passing attempts per team game by a QB in a season