| Year | Value | | 2016 | 0.11925603316272 | | 2015 | 0.12269878430044 | | 2014 | 0.10055759184679 | | 2013 | 0.10362855381172 | | 2012 | 0.095206359784834 | | 2011 | 0.095974406824847 | | 2010 | 0.069013478863295 | | 2009 | 0.068886580894042 | | 2008 | 0.067667803138745 | | 2007 | 0.068520226643827 | | 2006 | 0.070863609356177 | | 2003 | 0.057595724093443 | | 2002 | 0.058490819865822 | | 2001 | 0.058392455694724 | | 2000 | 0.059016548240126 | | 1999 | 0.060824290788769 | | 1998 | 0.07527286413248 | | 1997 | 0.07774185815998 | | 1996 | 0.064703560636942 | | 1995 | 0.064261983253327 |
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