Of course you skipped right over the part about the large number of self identified religious that had serious doubts.
I have never seen another survey that compares. I'd be interested to see exactly how they worded the questions, because you will usually see it the other way. People are much less likely to say they are atheists than they are to say they don't believe in a god.
Good numbers are impossible here. I've seen numbers that say just about anything.
But I really don't believe there is a god, and those people wouldn't be atheists.