According to a survey, published in late January 2018 by the Social Research Center along with the Australian National University, same-sex marriage was ranked the most historic event to have shaped the lives of Australians. 30% of the survey participants named the legalisation of same-sex marriage as the most historic event in their lifetime, 27% named the September 11 attacks, 13% named former Prime Minister Kevin Rudd's apology to indigenous Australians and another 13% named the Port Arthur massacre.