2014!

I've just realised that I'm not sure how to say 2014 in Japanese! Is it 'ni sen jū SHI' or 'ni sen jū YON'? I apologise if I'm asking for the obvious, but it's really bugging me. If there's a reason for why it is whichever one it is, then could you clear that up for me as well please? Thanks in advance :)