Well, many girls still want to be home for new years (which just 1 hour different from Germany). So you probably aren't going to get the numbers you have in oktober or november. Many of the clubs have new years parties nowadays, so they'll try to get girls to stay. For the last few years Sharks has been giving girls cash if they stay the two weeks around new year's eve. This has worked fairly well, although I believe the number were slightlty lower last time around. I have no idea if the club is going to do this again, but I'd say it is a good bet. If you go somewhere for new year's eve: go to Sharks, but you won't be the only one.