Yep, my mistake its 25 years, not 35. Though the difference doesn't negate the point that its been decades since a gun related massacre.
That linked source is for all massacres, most of which are not gun related and have < 6 deaths. Even if you include the 2002 Monash University shootings, its still 20 years.
If you look at [1], when the Australian gun laws came into effect, a year later the per capita number of gun related deaths halved. 25 years later and its halved again and the trend continues downwards. For reference the US numbers are here [2]. What is interesting is that when comparing the number of firearm possession per capita between the US and Australia, the US has roughly 10 times more guns [3]. Based on [1] and [2] the US has roughly 10 times the number of gun related deaths per capita. The reason why Australia has historically had less problems than the US with gun violence is that even at Australia's peak, it had 5 times fewer guns [4] than the US [5] did per capita.