Although the computer-generated charts are statistically meaningless, the persistence of number '17' in humans likely has its reason.

The first thing that comes to my mind is that this happens because 17 the number from 1 to 20 that we come into most rarely. When we learn multiplication at school, it doesn't have any factors so we tend to skip it, and for the same reason it's rare to encounter it in various problems. This happens also to '7', but '7' is small enough to occur in many occasions such as counting a number of items etc. So, maybe we are more inclined to pick '17' as 'random' because we rarely meet it. Maybe.