Are you including all the nations from Canada to the southern tip of South America? The answer will be staggeringly high.
There are no definitive statistics on this phenomenon.
10 out of 100
Around 87% according to a poll taken in New Jersey, Delaware, Alabama, North Dakota, California, and Michigan in 2008.
Adult lactose intolerance is the most common of all enzyme deficiencies, and it is estimated that 30-50 million Americans have this condition.