They blow them out at the end of the year.
This is actualy becoming quite a problem with boats. Most "new" boats you see at the shows this year were made in 07 or 08. Just never sold...the sales guys get kind of annoyed with you read the year off the tag on the transom and ask them for a discount since the boat is almost 3 years old.
I have noticed this on outboards as well, some are selling 2006 manufacture 2 strokes as new.