This question was prompted by me watching Ted Lasso. I'm four episodes into Season 3 and it's strongly implied that new signing Zava has scored all of Richmond's goals up to this point. It occurred to me how improbable (and unsustainable) this is - even the most prolific players will usually score only a fraction of their team's output across an entire season.
But it got me wondering: what's the highest percentage of a team's goals in one season to have been scored by a single player? To keep this reasonably-scoped, I'm only counting league goals, and I'm only counting top-flight professional leagues (I can narrow this further to just the "top five" leagues if that's still too broad).
The best I can find is William "Dixie" Dean in 1927/28, when he scored 60 of Everton's 102 goals (58.8%). Has anyone ever beaten this? This Reddit thread mentions a player in 1933/34 who scored 63.52% of Rouen's goals, but that wasn't in the top flight, so it doesn't count for the purposes of this question.