To clarify, the .8% is part of the 2.75% increase in Free Company houses since March. Personal housing tends to make the % of FC houses go down when new wards are released. As time advances, FC housing has always managed to reclaim the % it lost to personal housing.

The actual % of FC houses with less than 4 members, when compared to all the available plots, is 6.93% (27,173/391,680). If you want to ignore the JP servers, the % drops to 5.51% (11,445/207,360) for NA and EU combined. That % melts away if you start excluding FCs based on rank and/or even lower membership.