We want to survey how often each package is insalled.
Might http://popcon.debian.org/by_inst have the information you want?Popcon is a volentary system allowing debian users to report the packages they have installed. Thus the values are not perfect, but ware at least as good as the values you will recive.
The page I linked to has a list of packages sorted by number of users installed. One you remove all lines that begin with #, the 2nd feild is the package name, and the third is tyhe number of popcon users that have the package installed.