Is the US airbase in Kyrgyzstan completely empty?

Brief background first. Kyrgyzstan is currently the only country in the world to host both a Russian Airbase and a US Airbase: the Manas Transit center.  Manas is the main air route that the US uses to fly personnel and equipment in and out of Afghanistan. The Kyrgyzstan government has threatened to close the base several times, sometimes coinciding with newly generous aid packages from Russia. At present the US government has been given until June 2013 to close the base.

But putting aside the exciting story of Russian and US meddling in Central Asia, I have a much more mundane question. How come the US Department of Defense generally reports that it only has between 5 and 20 personnel present in Kyrgyzstan in its official statistics for each month between 2001 and the present? I'm not a military expert but I would have thought that it took more than  20 people to run an airbase that is reported to move up to 50,000 US and coalition troops to and from Afghanistan each month. Incidentally an ABC news report mentions that Manas is staffed by 1,200 people.

I came across this issue when checking the Heritage Foundation's compilation of the American troop deployment data.  Their data does seem to match the DoD's figures but I'd like to know whether these numbers have any validity or if the Kyrgyzstan data is a single oddity in an otherwise high quality dataset.

I'm interested in hearing if anyone has an explanation. Is there a counting technicality that makes the staff on base not technically active duty? Is the US downplaying its presence in Kyrgyzstan in its military statistics to try and avoid creating local tensions? Is the Manas airbase staffed by mercenaries or ghosts?

Sidenote: this was the first figure in the dataset that I checked because I've been following the disputes over the airbase for a while and wanted to see how large a force was deployed there.

The heritage data has also been used in a couple of academic articles so this is an issue that affects things other than my own research.