MELBOURNE (Reuters) - Nearly 12 million Australians, or 74.5 percent of eligible voters, have voted so far in a postal ballot on whether same-sex marriage should be legalised, the Bureau of Statistics said on Tuesday. The poll, which began last month, is non-binding, but the government has said it will put a proposal to parliament to make Australia the 25th nation to permit same-sex marriage, if a majority of voters are in favour of it. The postal survey closes on Nov 7. 