This is a somewhat difficult question.
My personal rules'o'thumb are:
Try to stay well clear of the minimum 12 hours a year, it's potential dangerous for you.
When taking your partner, do at least 50 hours a year.
When taking somebody else, do at least 100 hours a year.
When doing above 150 hours a year, ownership is more advisable than charter.
My personal average now after the high times is about 175 hours a year and I am comfortable with my skills for VFR. If I would still go IFR, 200 would be my minimum comfort level.
What is 'an average pilot'? Most pilots at my home field are called high-timers at 50 hours and the average may be somewhere around 35, which I see kind of critical.