The 2011 daily average volume dropped to 12.92 Mkm2, down 5.7% from last year. It's dropped 49% since 1979 (the first full-year of data), and has dropped 35% in just the last 10 years.
You can slice it up lots of ways -- I've chosen to look at each year in relation to the volume 10 years earlier:
By the way, PIOMAS recently published a paper in JGR about their model calibration and uncertainties. The preprint is here.