Several sites have their own meta questions for tracking changing statistics on beta sites. This is a community-wiki answer that lists them:
Still in beta:
The thing is, the stats on those linked pages are only crudely indicative. They're crude, but they're all that can be shared publicly. They are not yes/no indicators for graduation. They're crudely indicative, that's all.
Graduation needs a body of expert content, and a community to maintain and expand it. It's much harder to quantify that - there are some stats that can be manually generated by the SE developers, such as the number of high-rep users who visited in the last few weeks, and so on. And there are publicly-visible indicators such as the liveliness of the site meta and its chat. As more and more sites come through Area51 to graduation, we're all learning more about what indicators work, and what don't. I'd speculate that once Area 52 is launched, it will include a new set of indicators that capture that learning.
So, those linked posts are just a broad-brush view of where the site has come from, and is emphatically not a direct measure of how close it is to graduation. And whatever the indicators stand at, the message is still the same: if you want that site to thrive, keep attracting new expert users, keep adding expert content, and keep maintaining the existing content, through sharing, editing, voting, flagging, closing, reopening and deleting wherever appropriate.