The American College of Gastroenterology reports more than 60 million Americans experience heartburn at least once a month, and at least 15 million as often as daily. Diseases resulting from acid reflux are the most common gut complaint seen by hospital departments in the United States.
http://www.pressofatlanticcity.com/life/columns/acid-reflux-a-common-but-not-trivial-condition/article_ac60cd96-570f-55f8-9cf1-c659bb6a2e97.html
Acid reflux a common, but not trivial, condition