Do you know how I mentioned that how the numbers didn't add up?
Well, I got my support question answered.It turns out that while there are 1,0484,989 accounts, and I was right in my gues that only the journals that give gender information, 5,788,235 acounts, are personal journals.[1] The other half million or so are made up of communites, feeds, purged journals, and suspended accounts.
I also go my answer on why if there are more accounts that give age data than there are peronal journals: communites can have ages too.
Using this,
and the numbers from Part III, I'm guesing the real share of the teenage market is about a third. The people in their twenties is probably making up another third, and everyone not in those age brackets is is the last third. So it's not like four million didn't put their date of birth in their blog, but more like... a million and a half.
And the million of five and six year olds? There apparenlty used to be an option to put the date of the blog's creation for the birthdate. All those people just felt a little shy.
[1]This does include the massive amounts of RP journals.