When does the contribution rate fall? And agreement clause?!

hello, so for the first time I had taken out an insurance on my name. because I am 30 years old, I start at 75% (SF 1/2). I wanted to ask when exactly the contribution rate is lower? because in my contract this year it is at 75% and from 1.1.2014 it is at 60% (SF 1). I wonder what if I had signed the contract on the last day in December 2013, would I fall right next day to 60%? and what if I had my travel eug in this year sell and then buy another vehicle (and keep taking another insurance) do I start at 60% or 75% again? EDIT: and another question about the contract, one can tell me exactly what that means: picture in the appendix: