I know no human beings except BBC announcers who refer to next year as 'twenty twenty'!
Well, I'm here to tell you that I do, and so do many of my family and acquaintances (I have no friends – I wonder why?).
The year 1900 was without exception (as far as I know) always pronounced, “nineteen hundred”. 1951 was “nineteen fifty-one” and 1999 was “nineteen ninety-nine”. Then on the cusp of the year 2000, something peculiar happened. Many people defied convention and began to pronounce this as “two-thousand” instead of “twenty hundred” as might be reasonably expected (I think that Arthur C. Clarke should take some of the blame, or maybe Stanley Kubrick).
So, now we are stuck with this dual system of pronunciation. I shall continue to be a “twenty-hundred” man, What, may I ask, is easier to pronounce, “two thousand and twenty” (six syllables), or “twenty twenty” (four syllables)?