| Year | Value | | 2021 | 2.2076770691427 | | 2020 | 2.2307247849565 | | 2019 | 2.1115112532735 | | 2018 | 2.0480956940687 | | 2017 | 2.2164591086492 | | 2016 | 2.3692028074018 | | 2015 | 3.5379690132219 | | 2014 | 3.5151686882408 | | 2013 | 4.446122559446 | | 2012 | 4.7807757376819 | | 2011 | 4.1242135246268 | | 2004 | 10.467568555074 | | 2003 | 11.886883631662 | | 2002 | 13.302080552045 | | 1998 | 23.477371969076 | | 1997 | 29.142036978159 | | 1996 | 27.021567431391 | | 1995 | 20.936785228893 |
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