Gotta question about pool mining, hopefully I'm in the right thread.

I'm connected to http://pool.gridcoin.us, and everything is working swimmingly.  I even found a block.

But I am completely mystified about how the ranking of the leaderboard works, and how payouts are calculated.  The pool site is pretty bare-bones, so I couldn't find any kind of help or docs on there.

The column labeled "Boinc RAC" only appears to show the first few digits of my actual RAC.  For example, if my average daily credits show in the wallet as 210,000, this column shows it only as "2100"  (is that just a display bug, or are position and payouts being calculated only on the first 4 digits of my actual RAC?)

And are there really only 18 miners using that pool? (as of the time of this post)  I would've expected a lot more people to be mining in the pool.