What is more common these days MFM or FMF?

I completely agree that one women can easily satisfy several males at once. So MFM is more natural in this way. In that sense I would think that MFM was always more common and these days with women's "liberation" I tend to think it is just significantly more often between couples.
 
I agree MFM is more common, back before I got married in the late 80s and early 90s my girlfriend and I had a lot of group sex and 3somes where she was the only female, sometimes up to 10 guys, after I got married my wife and I have had a few 3somes and she too agrees that it's much better if it's only one female for a group of guys.
 
In our relationship it is MFM only, she has a boyfriend we often have MFM with. I have yet to do a FMF, she has however. She did it long before we met and very recently with our friends. At some point I may exercise my options with an FMF but from a math perspective I have one cock and women have several holes so it seems to make more sense for MFM.