It is, and out of those, only those who have set their location to be public. That might be the default, but I'm not sure, and I'm not going to register a new account just to find out. 9,000 players on EDSM sounds too low though: the last time Anthor made traffic videos, which was 3.5 years ago, the total CMDR count displayed was 50,000.
In any case, a better check of activity is tracking EDDN; EDAstro has an excellent tracker
here. You can see hourly statistics there, and keep in mind that EDDN reassigns all player IDs twice a day, to anonymize them. Which is the reason for the bumps on the hourly charts. Anyway, that's from all the sites which send player contributions to EDDN, not just one. (A lot of people use Inara though, which AFAIK doesn't handle system discoveries and such.)
As in most online games, only a small percentage of players upload data to third-party sites. You can see that here too, even if it's only the Steam charts that are available for comparison, and a lot of people don't use that. (FD have said so once too, but didn't say any numbers.) An interesting statistic though is that comparing Frontier's official numbers for how many systems were discovered at various points in time, then comparing that to how many of those systems were uploaded to EDDN, it's consistently around 40%. Meaning almost half of all systems are discovered by a minority of explorers, who are already a minority. In other words, those players who do share their finds with others tend to explore significantly more.
Well anyway, this was tangentially related, I'll let you guys get back to the main topic.