Looking at that map gives me bad dreams of supporting Arcview, Claritas Compass, and Mapinfo.
Anyone can make a map or that will suit thier needs by using switching around "median" rather than "average" and other tricks or having small differences show up as large.
My customers were all the news services and magazines in north america and our software "claritas compass" spanned across 38 cdroms.
They finally went to a browser based product.
My main pc at work ran WFW3.11, NT3.51, NT4.0, Win95 osr2, and win98SE.