The early years of SS COLA were quite high (I'm sure the "1970's Great Inflation" prompted the initial adjustments). If you ignore those years and start with 1984, the average COLA increase has been 2.6%. Of course nothing's guaranteed, and there were a few years with 0.0% COLA increase.
ďIt's a terrible thing, I think, in life to wait until you're ready. I have this feeling now that actually no one is ever ready to do anything. There is almost no such thing as ready. There is only now. And you may as well do it now. Generally speaking, now is as good a time as any.Ē - Hugh Laurie