I don't remember the percentages, but I recall reading some data gathered by an insurance company about how many people at 6 month and one year had moved from one insurance company, to the next. Of course it was just to calculate how much money they could save betting on us to move on to another employer/plan, lose a job, give up or die. It's so lucrative for them to sandbag, I just expect stupid delays, and they keep coming up with new ones.
Don't let them win. Hang in there, jump through their idiotic hoops, and make them pay for your new/healthy life.