Reliable, seemingly ubiased statistics regarding vegan/vegetarian percentages?

Can someone point me in the right direction here? I've been googling my buttocks off and the only related statistics that I can find are published by sources that can be discredited given their stance on the subject. I need some solid statistics regarding any/some/all of the following: the percentage of vegans/vegetarians in the U.S.A., Ohio, college students, gluten allergies or intolerance, statistics regarding WHY someone is vegan vegetarian, age demographics etc.

Pretty much as much as I can find that can't possibly be discredited or disregarded just because of the origin (like a study published by vegetarian times or herbivore magazine).

Any help would be amazing. I'm tired of sitting in front of this computer googling fruitlessly.

Thanks