Totally. But it is interesting to see how people think about this.
At one end of the scale you have people who only know users, and for whom this figure would undoubtedly be seen as higher. At the other end are those who do E in secret and so know relatively few users.
BT is right I guess, this thread probably contributes no real value to harm reduction, especially since rumors spread from the most unlikely sources and it would be unfortunate if any of the figures mentioned here were quoted as fact.
Still, I'd be surprised if people like NDARC or the Feds don't have some estimation based on collaborative studies. If not then perhaps it might make a good post grad topic for someone.