Garthanos
Arcadian Knight
Here is one sourceIf you can dig up the source I'd like to see it, but in my research it still isn't normal or average, even at the college/pro level. I'll agree it isn't far off, however.

NFL combine: Data suggests broad jump might be best indicator of running back success
The importance of the NFL combine can be overblown, but a PennLive data analysis highlighted a few trends.
For me It is nothing like legendary.