We know, year zero doesn't exist. It didn't stop everyone celebrating the new millennium a year early though did it?
As far as popular culture/media is concerned when the third digit is on the cusp of change, we move into a new decade. Wrong but we still do it. Check out the amount of 'noughties' retrospectives that were in magazines and newspapers last December.
I made this point over Christmas and was called an anal c*nt. Then I said: how can you possibly have an anal c*nt? [iWoosh.[/i