1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 12.2417 13.0917 12.8 12.9667 12.7417 14.875 13.3417 15.5 14.3583 12.3167 14.9667 12.1083 12.5167 16.05 15.1333 12.8833 19.125 18.2917 12.8083 16.5 Year $/cwt