1)number is closer to 30k
2) over a third of that is just in the past 2 years
3) 2012-13-14 saw the numbers double every year and 2015 is on track for that too
4) the percent that come back is maximum 4%. That's hardly a high percentage
Where did you get your numbers from? Before 2012 it was less than a thousand a year. 2012: 1500, 2013: 3000, 2014: 7000.
about #4 you have no idea what you're talking about. Sorry.
(If you ask how do I know, I lived in France for several years and a large part of my family lives there and I still go there a couple times a year)