It's 2006, but just barely. Overall, 2005 was a relatively shit year, but this one is looking even worse. It's also looking like Dean's last.
A creature invades the bunker and attacks Dean. Then he names it.
Sam didn't need his gun, or Ruby's knife or Cas' blade tonight. He had the power running through his veins to end it all tonight. This sacrifice would be the most righteous thing the demons he drained could ever do. Killing Lilith, avenging his brother, tabula rasa.