Back in 2010, Parliament changed the law around advance voting. Where previously you had to make a statutory declaration that you would be unable to vote on election day, now you could just go ahead and do it. The result was predictable: in 2011, advance votes rose from 236,000 to 287,000 - 12.5% of the total.
This year, voters are smashing that record. After only 5 days, over 70,000 people have already advance-voted - an increase of 150 percent over last election. If this trend continues, we could easily see half a million advance voters, and over 20% of us casting our votes in advance.
As for why, there's definitely greater knowledge of the law this time round. But there's also a definite "vote early" campaign from the left, as part of their general get out the vote efforts. The question is how much of it represents an increase in turnout versus people simply getting it done early. We won't know until election day, but given that increased turnout tends to favour the left, the government might be getting nervous about now. Which means its probably only a matter of time before we start seeing the usual right-wing suspects calling for restoring restrictions on early voting...