
GRID-Arendal, a collaborating center of the United Nations Environment Programme (UNEP), has a fantastic website with detailed statistical information for several regions in and around Europe, including the Caspian Sea.
This graph represents the illegal caviar trade in the Caspian region between 2000 and 2005. (Click for a full-scale image)

Another graph represents the legal international caviar trade between 1998 and 2003 for caviar originating from the Caspian Sea. In 2003, 83% of the world caviar trade consisted of caviar from the Caspian Sea.
A Very informative website for those that are in interested in Caviar, the Caspian Sea, and historical data.