I'd be interested in a number (or at least an estimate) of how many field agents Men In Black (MIB) agency has.
I'm specifically referring to field agents, as opposed to guys on cleanup crews/headquarters workers/lab guys etc...
This can be something from an in-universe source (movies, comics, cartoons), or official out-of-universe source (DVD commentary, interviews etc...) or a detailed well reasoned logical estimate (in the vein of the recent answers about crew size of SG1 spaceships or # of people who know about StarGate).
To aid in the latter type of estimate, one possibly helpful fact is the quote from the movie:
At any given time there are approximately 1500 aliens on the planet
For the purposes of estimates, I am OK with only counting people based in NYC office if your starting data involves logistical data/details from NYC headquarters building (e.g. size of locker room, armory details etc...).
One of the possible answers may be "25" - based on the agent naming convention (A-Z, with Z of course taken up by no-longer-an-agent agency boss Zed). But realistically speaking, I don't see how that'd be even remotely enough to deal with 1500 aliens PLUS uncountable "happening every day" threats/emergencies. If you can show why the latter "too little" objection can be overcome, feel free to run away with 31 as the basis for your answer.
The impetus for the question is Xantec's answer which posed the limited amount of available agents as possible reason for Agent J being chosen as a senior partner in the pair of agents at the end of MIB1 despite being a rookie.