Indeed, the Finnish market is pretty skewed, as far as I know, it's the only market where Windows Mobile is @ +30% market share for smart phones (because of Nokia loyalty).
It skews the app market too, probably no one outside of Finland cares about Windows Mobile but in Finland supporting it is a big deal.
There are some other markets where Windows Phone is in 2nd place (ahead of iPhones) and so supporting it is indeed a big deal. Italy, some eastern European countries, Southeast Asian countries, South America, possibly Russia...
It skews the app market too, probably no one outside of Finland cares about Windows Mobile but in Finland supporting it is a big deal.