I'm going to have to partially dispute you. I'll get to the point, but first let's define clearly, what is an allergy, an intolerance and what's coeliac disease.

Some raw numbers, wheat (gluten) allergies affect less than 1% of the population (it's something like .48%). It's not something you can hide, you either swell up and stop breathing when you come in contact with it or you don't. It's actually hard to find in adults as most people grow out of it when they enter puberty. If you don't die within a short time from eating wheat (without treatment) due to an IgE antibody surge, you aren't allergic -- full stop. (yes, there are emergent allergies that occur later in life, gluten allergies are generally not considered to be in the class of those types of allergies). http://en.wikipedia.org/wiki/IgE

Wheat (gluten) intolerance is more prevalent. But so are most food intolerances. For example, it's generally considered that 3/4 of the adult population of the U.S. has a dairy intolerance. Intolerance != allergy. You can eat foods you are intolerant to. It might give you an upset stomach or bad gas or some such, maybe diarrhea and a really bad headache. But by those symptoms most of us are intolerant of high fiber diets, coffee and all forms of strong alcohol. It might be worse, like dizziness or some such, but if you don't have IgE antibodies in your system after contact with the suspect food it's not an allergy. In other words, probably 100% of the population is intolerant of some food some of the time. People often mistake "allergic" with "intolerant". Allergies are far more severe and critical than intolerance. Intolerance comes from a lack of an ability to process a given external agent due to some genetic predisposition -- like how many East Asians can't process alcohol properly or MSG makes my Aunt get a headache.

Coeliac disease occurs in about .75% of the population (as identified so far). It is a distinct and different disease from gluten allergies and gluten intolerances. Coeliac disease is an autoimmune disorder where the body destroys the lining (the villi) of the intestine as a response to the presence of the byproduct of gluten after it's been improperly modified by a faulty enzyme causing an IgA antibody flareup in the gut. It's only now really being diagnosed as it is easily confused with other bowel diseases prior (like IBS or Ulcerative colitis or granulomatous among others). Recent IgA antibody tests do a pretty good job of positively identifying the disease (but you have to be on a gluten rich diet for it to work, otherwise you'll have no antibodies to test for!). The number may grow, but probably not much, even wildly high estimates put it at under 3% of very localized, genetically predisposed populations. Whatever the case, it presents as a chronic disease, not an allergy. You don't eat wheat, then blow up, stop breathing and die. Your intestine slowly rots away, you become malnourished and your feces turns white.

Likewise, food intolerance != Coeliac disease != food allergy. The three things are different. You may as well bundle people with sun allergies and who have dry skin from harsh soap into your numbers if you are going to do that. The only common factor is that the causative agent is the same -- wheat. But even if you add up all the numbers of people with wheat allergies and people with coeliac disease, you likely end up with something less than 3-4% of the general population.

"Dangerous Grains" is an interesting book. But if all you look for is a duck, suddenly everything starts to look like a duck. I'd caution anyone from self-diagnosing based on descriptions of layman oriented symptoms from a book written to popularize an interesting theory. Many things cause precisely the same symptoms as gluten intolerance (and visa-versa). Dangerous Grains, while an great way to popularize recent science with the layman, is not the same as medical science.