Scott Morrison's government has been elected with one of the lowest voter turnouts since the advent of compulsory voting as the nation's young turned their back on democracy after enrolling in droves for the same-sex marriage postal survey.

A special breakdown of voting figures from the May 18 poll suggests less than 91 per cent of people cast a ballot, formal or informal.

Scott Morrison's election victory came despite a fall in turnout and an increase in informal votes. Credit:AAP

It is on track to be lower than the 2016 election and the worst result since the mid-1920s (excluding some years when up to a dozen seats had just one candidate) when compulsory voting was introduced after just 55 per cent of Australians voted at the 1922 general election.

Nearly 16.5 million - 96.8 per cent of eligible voters - were enrolled to vote, the most complete the electoral roll has been since Federation. This was in part due to an influx of younger voters who came onto the roll for the same-sex marriage postal survey in 2017.