I don't know an exact ratio, but I'll look into it. I don't know if it's as simple as just looking at a ratio, without taking base/out states and game situations into account.
I do know that the last time I checked, the Sox were the 4th best in the majors in extra base taken %, and that their UBR (extra base taken runs) and wSB (stolen base runs) were both positive. It is by a small amount, but overall positive nonetheless.