I wonder also how many people may have just an image of Dorje Shugden, or just recite his mantra occasionally alongside their other prayers, or just make offerings once in a while at a temple - would they be considered practitioners and be counted in as well? If so, then you might want to take into account quite a few million people in places like China as well, for example - i have heard that there is a presence of the great king there, but it is serious practice yet - just the occasional visit to the temple, offering incense and that kind of traditional thing (for now).