McCain's Tax Returns

I'm with Josh Marshall on this one - the McCain campaign's release of two years of individual tax returns for John McCain is insufficient, and would be unacceptable from any other candidate. Given how little information is actually conveyed in his tax returns, I am left wondering about this claim:

Senator and Mrs. McCain have kept their personal finances separate throughout their 27-year marriage. Accordingly, they have for many years filed separate tax returns.

For how "many" years? Two? Because if his other tax returns look like the last two, there's no conceivable reason not to release them, even if we're going to play the "privacy of our children" game with Cindy's.