What is League Average Scouting Grade letter?

[Iorwerth]

In draft scouting, the system uses a letter grade going from A= to F (missing out E as far as I can tell at moment). I know this is rating the player against players in the league, not draft, within the same position. But what grade corresponds to the league average? Is it B-, C+, C, C- etc? Seems like this would be something that I should know as a GM, as would be rather annoyed in real life if my scouts came back with such a report but refused to tell me what the league average grade was