Contrary to popular belief, and due to the fact that there never was a year zero (history goes from 1 BC to 1 AD – or 1 BCE to 1 CE) without stopping, the hundreth year of each count – that is, the years that actually end in 00 – is a part of the previous century. So despite all the millenial madness that attended the last day of 1999 and the first day of 2000, the Twenty-First century CE did not actually begin for another year.
Nor will it end until December 31st, 2100 – and if you’re still around that night, you can bore everyone with calendrical pedantry if that’s what floats your boat.
As mentioned in: