I would say that if you are consistently making 35% a year on unmargined capital, you are a great trader... consistently inflated triple figure % returns are simply not feasible, in my view... that it not to say that the occasional home run year is not possible, cos I have myself done 200%+ in a few years... but we are talking the long-run average here...
Assuming that most traders are using around 2:1 margin, I would say a 70% return on capital per year (consistently), assuming such margin, is fantastic...
e.g. Starting balance $50k, trading on 2:1 margin, getting 35% on your own capital and 70% on margin... and also reinvesting (a simplistic assumption, I know)...
At end of 10 years $50,000*(1.7^10) = $10 million...