The international larp census of 2014 has been launched, this is what the authors have to say about why you should answer it:
Although some countries have rough estimates of their larp population, there has not been a comprehensive global census taken of self-identifying larpers on this scale. We really want to count everyone who larps, has larped, and wants to larp.
The information we acquire will be publicly shared so scholars can analyze the data and make conclusions that will, hopefully, increase both the quantity and quality of larps around the globe.
Check out and take the census here:
http://www.larpcensus.org/