The Prevalence Of Celiac Disease In The United States, The American Journal of Gastroenterology, October 2012
Conclusions: The prevalence of CD in the United States was 0.71% (1 in 141), similar to that found in several European countries.
Prevalence of Wheat Allergy In Japanese Adults, Alergology International, 2012
Conclusions: The prevalence of wheat allergy in Japanese adults was found to be 0.21% by using a combination of questionnaire-based examination, skin prick test and serum omega-5 gliadin-specific IgE test.
Prevalence Of Gluten-Free Diet Adherence Among Individuals Without Celiac Disease In The USA: Results From The Continuous National Health And Nutrition Examination Survey 2009-2010, Scandinavian Journal of Gastroenterology, August 2013
Conclusions: The estimated national prevalence of non-celiac gluten sensitivity is 0.548%, approximately half that of celiac disease.
From these numbers (celiac disease 0.71%, wheat allergy 0.21%, non-celiac gluten sensitivity 0.55%), it appears that sensitivity to eating wheat is not common. Yet my grocery store just installed almost a whole aisle of gluten-free foods.