Works by dividing the days since 2000 by 365 and rounding it so the string does not get so long.
I was planning on using @djpro's pen text counter to make it a bit more elegant and #cool, but for inexplicable (by my knowledge) reasons it would not cooperate so you're left with this. You can use for whatever weird thing you come up with that requires this, with credit, though I cannot see the use outside of a little gimmick to be honest.