I still think that site is the best you'll find. I could be thinking of someone else here but I seem to recall GJ's point was a lot of City's attendances were under-reported(the Swales era for example). So if they are slightly off, it's through no fault of the site and nobody else can claim their figures are more accurate because they'd be guessing(since that's what the club reported).
Regarding the seasons in the topflight(although Wiki is also a reliable source for that too). Yep, I like to point that out too, to the City bingo players.
As we know, 5 of City's seasons outside of the topflight came in the first decade of the PL era, a real low point(you could argue the worst) for the club. Without those troubles, City would have a higher total than the rags. Those 4 seasons in a row without topflight football in the 90s, were a club record since they first reached that level back in 1899. I think that says something about City as a club. There can't be many clubs who fair better than that. Liverpool and United don't for example. Only Arsenal from the big 6 can claim that, 2 seasons in a row is as bad as it's got for them, since their promotion in 1904. Everton are another(Villa aren't), with 3 in a row as their worst. That's some consistency, to be fair to them.
I don't even know where the term "yo-yo club" comes from for City, considering the fact that City are in the top 6 for most topflight seasons in all of English football(how can that be?).
A yo-yo to me, has to be where a club comes up and goes straight back down again. Or do they have to be promoted, relegated and promoted again? Either way, that's only happened once to City by my reckoning. At the start of the 00s. They came close to doing that in the 80s(2 seasons before going back down) but other than that I just don't see any justification for it. IMO, the people who say that are those that took great glee in the City fans anguish as they got relegated again in the 2000/01 season, just when the fans thought the dark times were over. It just shows what empty heads they are. If they form the whole basis of their opinions of a club, though such a narrow scope. "That's all I remember, so that's all City are".