1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 3.865 3.95833 3.90583 3.6625 3.965 4.50583 5.92583 4.10333 3.54167 2.86167 3.09667 3.37667 3.79917 3.96333 4.12667 3.2075 4.34083 6.27417 8.12167 5.569 Year $/cwt