The U.S. has three times as many smartphone users as the U.K. has people17
Of course, the fact that the U.S. is number 13 is quite impressive, because it is by far the most populous country on the list. The second most populous is the United Kingdom, which has about one-fifth the population of the U.S., and has 62% smartphone penetration. In fact, at 56.4% smartphone penetration in the U.S., that would mean somewhere around 180 million people on the U.S. have a smartphones. So, that would mean there are almost three times as many people with smartphones in the U.S. as there are people living in the U.K.
If you asked around, we would guess that South Korea would be widely assumed to be number one on this list, but Samsung's home was beaten out by less than 1% by the United Arab Emirates. The UAE of course does have the benefit of having under 8 million people living there, which makes it easier to get 73.8% smartphone penetration.