Well, I have been watching and waiting for a couple of trips and this has been the trend:
In October 2001 - they opened up through early April 2002.
In December 2001 - they opened up through early June 2002.
And, in February 2002 - they opened up through early August 2002.
I would bet that next month (April), they will add 2 months through early October.
But, who knows?