| Year | Value | | 2014 | 1,677.5970015608 | | 2013 | 1,978.1010770864 | | 2012 | 1,646.5748072216 | | 2011 | 1,419.8441732735 | | 2010 | 1,483.0297791615 | | 2009 | 1,658.8604082876 | | 2008 | 1,472.1120698244 | | 2007 | 1,463.6673433395 | | 2006 | 1,422.1985333156 | | 2005 | 1,392.1123495422 | | 2004 | 1,405.5301398269 | | 2003 | 1,293.4741138224 | | 2002 | 1,210.4972898899 | | 2001 | 1,164.6319660827 | | 2000 | 1,099.6042235457 | | 1999 | 1,022.1346238202 | | 1998 | 1,043.6679613867 | | 1997 | 978.7853674984 | | 1996 | 915.19932447166 | | 1995 | 890.75519196908 | | 1994 | 918.49656544803 | | 1993 | 882.19484606726 | | 1992 | 888.29762897737 | | 1991 | 819.21853360607 | | 1990 | 737.99417655504 | | 1989 | 697.56489927178 | | 1988 | 684.22988855695 | | 1987 | 801.40220803516 | | 1986 | 709.76533648558 | | 1985 | 623.51585662297 | | 1984 | 601.36284651146 | | 1983 | 587.33856438616 | | 1982 | 590.41513808774 | | 1981 | 555.58551692348 |
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