Before we begin, I believe that its important to note a huge difference between offensive and defensive penalties. Many offensive penalties function as effectively turnovers. Defensive penalties are almost always a reliable first down for the offense – a bad outcome but nowhere near as consequential. So its not as big of a deal to have defensive penalties as it is to have offensive ones.
The Denver Broncos had 38 accepted defensive penalties, along with 5 declined ones. Minnesota had the fewest defensive penalties with 21, while Cleveland led the league with 57. The average was 38 accepted penalties, just where Denver was.