SAYING YEARS IN ENGLISH

I've just read an interesting entry in David Crystal's blog about the way that speakers of English will opt for to call the years from 2010, On tens, teens, or whatever.

I thought that the option of naming the years after 1999 in units, e.g. "two thousand and nine", was something fixed but I see that usage spread will definitely determine the standard form.

In the thread of comments following the post, Crystal adds that "rhythm is an important factor (...) The more that expressions conform to an iambic pattern, the more people like it".