Nope. That number [68,772 members now on ET] means the registered people in the last 7 years, and you have to subtract the multiple aliases. So take off 10%...
That doesn't work, because posters read more threads than they post in...
All these numbers are only meaningful in a given timeframe. Let's say last week there were 3400 visitors and 780 of them posted at least once. (made up numbers)
That's why that 68K members claim is meaningless. It really means 68 K screennames (not different people) ever registered....