Damn, fucked up at 70. Wanted to reach 100, but takes too long to get there so won't give it another try.
A weird thing started happening at like 40+ though, I was concentrating so hard that everything around the point I was staring at faded out into white, all I could see was the hole and whatever came out. I know it's like an eye illusion thing, but still cool.
Give it a try, just stare at the hole and don't look anywhere else for a few dozen clicks (make sure your cursor is not on the hole).