Every decade around this time, we get pedants who point out that since there was no Year 0, decades/centuries/millenniums start on 1.
I observe that the Gregorian Calendar we use started in 1582, so not only was there no year 0, there was no year 1, year 2, year 3, ..., or year 1581. Therefore, true pendants should be insisting that decades start on twos, and centuries start on 82s, and millennia start on 582s!
Insisting they start on 1 actually has no logic to it at all, if you're going to be concerned about decades and centuries lining up with "when the calendar started", because the calendar did not start on 1, either. No matter how you slice it, we started in the middle of a decade/century/millennium, and so it might as well be the pretty and universally-agreed-upon 0 rather than 1.