Doing a naive "start at the origin, iterate over the stars moving half way towards each time" thing, with various orders of the data (ORDER BY in the SQL on various fields), yields an answer around 90 to 95 : -70 to -65 : 10 to 15. That's someplace around "Crucis Sector PC-V a2-0".
That seem plausible to me. If you look at a visualisation of the gamma systems from FD it looks like a large sphere centred on Sol and then a smaller, intersecting sphere a little way off to one side. That second region would pull the average coordinates in that direction slightly.