Here is an article about where some Europeans prefer to vacation and their preferences for shelter.

http://elpais.com/elpais/2015/05/04/...32_627876.html

I would take that article with a large pinch of salt.
9 out of 10 Dutch won't be spending their vacation outside the Netherlands. Maybe 50% will.
Many prefer staying in the Netherlands, or simply can't afford to go somewhere else.
When they do go abroad Germany, Belgium, and France are the favourite destinations.

Agreed, many dutch caravans end up just across the border, no need to drive all the way to Spain. I suspect they are looking at airline user info. Equally I've met a few French people who say they have never left the country but assume Belgium, northern Italy and southern Netherlands is "the country"