1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 29.72 36.9342 35.545 37.2758 39.605 42.9167 40.0942 46.8842 53.7133 54.7463 49.0806 49.5121 51.4365 44.1375 Year $/cwt