Australia is at 0, since 1994.
I think you meant to say 0 rampage shootings in Australia since 1996 when Martin Bryant shot 35 people to death. But it isn't quite correct.
In 2002 there was a shooting spree by Huan Yun Xiang, a student at Monash University, but he only killed 2 people.
And of course the 2014 Sydney hostage crisis where 3 people were shot to death and 4 others wounded.
Also in 2014, there were 8 dead in Lockhart, NSW from a murder-suicide shooting spree by Geoff Hunt who killed his wife and three children before turning the gun on himself.
Even without guns, in 2014, 8 children aged 18 months to 15 years were stabbed to death in Cairns by Raina Mersane Ina Thaiday.