That's actually a matter for debate.......
By: NickO : January 1st, 2020-18:17
While many agree with you, it should be noted that for computational reasons, astronomical year numbering and the "ISO 8601" standard designate years so that AD 1=year 1, 1 BC=year 0, 2 BC=year −1, etc. In this instance, a new decade would indeed start wi...