Adam Vinatieri, arguably the greatest kicker in NFL history, averaged 29.79 (30) field goal attempts per season. He has a career 83.8% field goal make percentage.
Grupe at 80% aint bad. Yes he's had some very untimely misses, but when you consider how bad the Saints red zone offense is (29th)... Grupe is under an unfair amount of pressure to have to make every single kick because he's probably going to be most, possibly all the points the Saints score in a game.