I took the latest available data sets, got the list of towns using electronic voting from the official site, completed and corrected town names by hand.
The significant factors I found are, in order of decreasing signifiance:
- Percent of people holding bachelor's degrees,
- Voting method.
I'd like someone who know his statistics well to check the data and tell us if the voting method is indeed significant. The fitted models are linear and for all I know, it could be acting as a non-linear proxy for population size or some other funny explanation...
Anyway the new data is available here, feel free to check, improve and re-publish it. Note that you need the maptools R package. You can install it by typing install.packages(c("maptools", "maps"),dependencies=T)) in R.