I'm looking for a way to determine if a polyline is "mostly within" a polygon. Since mostly within is arbitrary, I would need be able to enter a percentage at its execution. 

I thought there might have been an option in ArcMap using Select By Location, but there doesn't seem to be. There are similar methods, such as "completely within" but I don't see how I can use any of them to achieve what I'm looking for.

Does this functionality or a method exist to achieve this?