In a rare moment of disclosure, the normally tight-lipped Twitter announced last week that it now has 100 million active users. Who are all those people, and how often are they tweeting? Here, a brief guide, by the numbers, to the micro-blogging site's big milestone:

26 million
Number of active users Twitter had at the end of 2009

60 million
Number of users who have logged in and tweeted in the past month

40 million
Number of users who have logged in but not tweeted anything themselves in the past month

400 million
Number of people who have visited in the past month, according to Google Analytics. Users don't have to log in to read most Twitter content.

Percentage of NBA players who are on Twitter

Percentage of congressional members in the U.S. House who are on Twitter

Approximate number of Twitter followers to whom former Rep. Anthony Weiner (D-N.Y.) sent a lewd photo of himself in May

Number of Twitter followers the lewd tweet was meant for

Percentage of senators who are on Twitter

Number of followers Sen. John McCain (R-Ariz.) has. That makes @SenJohnMcCain the most popular tweeter in Congress, according to the website Tweet Congress.

Percentage of the Billboard Top 100 musicians who are on Twitter

Number of followers Lady Gaga has

Percentage of the top Food Network personalities who are on Twitter

Number of followers Paula Deen has

230 million
Average number of tweets sent each day, adding up to more than 5 billion tweets per month

Record number of tweets per second — a mark Twitter hit two weeks ago

$400 million
Amount of venture capital Twitter raised in its latest round of funding, which it wrapped up last week, on top of another recent round of fund-raising that brought in another $400 million. "Now we have what can only be referred to as a truckload of money in the bank," says CEO Dick Costolo.

$8 billion
Recent valuation of Twitter in light of the latest rounds of funding

$3.7 billion
What the company was valued at last December

$200 million
Twitter's projected revenue for 2011. "Unlike Zynga and Facebook, Twitter is still experimenting with business models and isn't cash flow positive," says Mashable's Ben Parr.

Sources: All Things D, Business Insider, Mashable, NY Times, Paid Content, PC Mag, Reuters, Search Engine Journal, Twitter, Tweet Congress, VentureBeat