Based on article in npr
When we ring in the new year and welcome 2020, should we also celebrate a new decade?
Confusion over the answer is similar to the uncertainty that hung over historic events from the millennium to the 2009-2010 changeover.
According to the Farmers' Almanac Sandi Duncan ,"The next decade won't start until Jan. 1, 2021."
When asked about the dispute, Rick Fienberg of the American Astronomical Society says he doesn't think his group has adopted an official position on the matter — but he adds, "History is clear: Because there was no Year Zero, the first decade of the common era (CE or AD) was years 1 to 10, the second decade was years 11 to 20, and the next decade will be years 2021 to 2030."
The debate has often turned fractious. And that could be because there's something personal at stake. After all, part of the definition of a decade is its cultural significance — the meaning it has for all of us who lived through it.
Whatever you feel, you may/may not be correct.
HAPPY NEW YEAR