This is the problem with only having a single sample to work with.That we know of. Other intelligent species could have evolved and been wiped out without a trace many times over in those 4 billion years and we wouldn't know. We ourselves won't make it to 400,000 years by the looks of it. Imagine how many other species may have had the same fate.
Also, intelligent life doesn't necessarily equal development of technology and/or civilization. There could be entire planets inhabited by highly intelligent dolphins and we wouldn't know by just flying over and looking out the window.
Regarding item 6; Development of technolocal civilization, meaning radio communication.
Humans have been around for 300,000 years, we've had radio for about 100. Obviously somewhat less than the 50% cited in the OP's source. If we use civilization in the more general sense we've had that for 5000 years.
The major issue with these figures is that they treat the development of intelligent life and civilization as factors of time.
That isn't true for us and isn't likely to be true elsewhere in the galaxy.