And so with years. There was no such time as "the year 000". Zero has no function in counting, since it declares that there is nothing to count. Year 10 is the tenth and last of a decade, just as year 2000, which begins in a few days, is the last of 2,000 years. We won't start the third millennium, or the 21st century, until 1 January 2001. Sorry.
St Margarets, Middlesex