| Year | Value | | 2022 | 1.6964362914736 | | 2021 | 2.1503455605749 | | 2020 | 1.8590282441758 | | 2019 | 1.7899535169433 | | 2018 | 1.3403639214496 | | 2017 | 1.3426973948828 | | 2016 | 1.4716379600487 | | 2015 | 1.5753167789091 | | 2014 | 2.0296543954646 | | 2013 | 2.8339082702339 | | 2012 | 1.7028452020622 | | 2011 | 2.0484012478066 | | 2010 | 2.4099601751464 | | 2009 | 1.7479707408184 | | 2008 | 1.5498809938306 | | 2007 | 1.0890772448248 | | 2005 | 1.0897599334416 | | 2004 | 1.1530880040695 | | 2003 | 1.263854401193 | | 2002 | 1.0869555696034 | | 1996 | 1.2101920711955 | | 1995 | 1.1667819199095 | | 1994 | 1.2558826516793 | | 1993 | 1.4970878451711 | | 1992 | 1.6421253174142 | | 1991 | 1.5680693419668 |
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