Well, it's "two thousand seventeen," according to people who like to say things the long way. Why not "twenty seventeen"?
But syllables are cheap, you say. Our housing costs are skyrocketing and the Fed has raised interest rates, but syllables? They're free! Heck, why not add another one and say it's "two thousand *and* seventeen."
Well I'll tell you why not: I'm busy! Aren't you? Do you even realize how many cat videos you haven't seen yet?
But the crazy thing is, even news announcers say "two-thousand" instead of "twenty" when they say the year. And those people are professional talkers whose air time is managed down to the micro-second, so if they don't see the gross wastefulness of their ways, this may be a lost cause.
Now I know what you're thinking -- saying "two thousand seventeen" instead of "twenty seventeen" just takes, what? A tenth of a second longer? Well you're not looking at the big picture. Say it ten times a day for a decade, that's an hour of your short life you're not gonna get back. Multiply that by more than three hundred million native English speakers and you can see the scale of the problem.