I’ve posted here a document with tables summarising the measurable variations in enrolment, effective voter influence and actual representation in the major nations for which I have good data.
The data uses includes election results from around 2000 onward for Australia, including most of its states and territories, the UK, France, Canada, the US, India, Pakistan, Malaysia and Malta.
The table shows measures of variation in voter influence in terms of electoral division populations, variations of influence in terms of the marginality of seat victories, and the extent of actual representation of registered voters in terms of having a representative from their preferred political party.
Results are shown up to mid-October 2016 and including the Irish, Australian and ACT elections held during 2016.