2013
2013-05-19 -:- The last time we saw more than 5,500 players online at once (online population was 9,255).
2013-05-23 -:- The last time we saw more than 5,000 players online at once (four days later).
2013-06-06 -:- The last time we saw more than 4,500 players online at once (two weeks later).
2013-08-08 -:- The last time we saw more than 4,000 players online at once (two months, two days later).
2013-08-15 -:- The last time we saw more than 3,500 players online at once (one week later).

2014
2014-08-07 -:- The last time we saw more than 3,000 players online at once (eleven months, twenty-three days later).
2014-09-18 -:- The last time we saw more than 2,500 players online at once (forty-two days later).

Today
8 Months, 22 Days later:
We're sitting at 2,437 players currently online.

The highest since 2014-11-06, which had 2,472 players.
Which was 7 months, 3 days ago.

The numbers might look bad, sure, but when you consider that if Dust 514 were a game on Steam -right now-, this is what it'd look like:

#51: Total War: Attila - 2,849 players
#52: Space Engineers - 2,661 players
#53: The Witcher 2: Assassins of Kings Enhanced Edition - 2,634 players
#54: Neverwinter - 2,629 players
#55: Tom Clancy's: Ghost Recon Phantoms - 2,623 players
#56: ArcheAge - 2,616 players
#57: Planetside 2 - 2,501 players
#58: Dust 514 - 2,472 players
#59: Dark Souls: Prepare to Die Edition - 2,448 players
#60: NBA 2K15 - 2,394 players

And then there's Evolve which ranks #238 with 379 players currently online. Which came out about four months ago.