| Year | Value | | 2011 | 453.74331656742 | | 2010 | 451.16243103261 | | 2009 | 542.23707224418 | | 2008 | 405.80589971759 | | 2007 | 398.76406227331 | | 2006 | 372.41770835738 | | 2005 | 338.42784708715 | | 2004 | 345.66194234183 | | 2003 | 280.49861031039 | | 2002 | 247.86329734712 | | 2001 | 262.76197931992 | | 2000 | 252.68771474009 | | 1999 | 254.10161242175 | | 1998 | 269.48167284659 | | 1997 | 246.21943713586 | | 1996 | 250.74456545357 | | 1995 | 223.73023386825 | | 1994 | 223.74011504796 | | 1993 | 204.15164730328 |
|