Germanys top Woman Magazine "Peta" has made a big survey about sex with the ex.

"22% of all girls had at leas one time sex with her ex bf also if they were in a new relationship" 

 For thesurvey the gewis institute asked 1.143 People between 25 and 39 for the survey, the result gives realy big hope to a lot of ex boyfriends and a shock to the new boyfriends. Some men also think to quit the relationship becouse 22% chance of sex is better than no sex at all :-)

Source 

http://www.n-tv.de/804042.html

 Petra ex boyfriend survey (German)