All BOINC projects are plagued with bogus users set up by spam bots. These multitudinous users never have any credit.
I do not know whether the statistics sites count these users or not. If they do, that by itself would push all normal users into at least the 95th percentile.
Beyond that, many users will only briefly join a project. Some want to see what the project is like, and leave if it doesn't suit their needs. Others stay long enough to get the first badge. Others stay just long enough to get 100 hours for a WUProp star. And an infinite number of other reasons.
The bottom line is that most of the users don't have a lot of credit at any given project.
My lucky number is 75898524288+1