Rating subject is a quite popular one on the CodeForces, and the last few discussions I saw where about — if you can't go up to Div.1 after a year of competing here, you need to drop this occupation.
In a year you can spend just about 10 hours on trainings, or even more than 800 hours, so measuring your results in this way is not a deal. That's why I want to suggest another shitty method of measuring the results — statistical expectation of your rating basing on the number of rated contests you competed. Calculations where made for Active users (last 6 months) and all the users ever competed here.
Table number one (blue line — contests, numbers — expected rating):
You can mention, that active users have a higher value of expected rating. This can be caused by rating inflation, or by the fact, that active users have better results, and those who had worse ones just dropped this activity
Table number two (rating and number of contests, necessary to achieve it):
Somewhere near 2000 rating points there is a tendency change, where number of contests is not playing a significant role anymore. I can confirm this from my own experience — it's about rating you can gain, mostly knowing nothing about algorithms, without regular solving problems archives — just competing and competing
Table number three (rating by number of contests):