| Year | Value | | 2022 | 35.245794565151 | | 2021 | 42.575720841156 | | 2020 | 41.801640169421 | | 2019 | 33.904800271312 | | 2018 | 29.211289501929 | | 2017 | 29.667076984781 | | 2016 | 30.033327226285 | | 2015 | 29.005674888615 | | 2014 | 31.346416683274 | | 2013 | 32.121645275477 | | 2012 | 37.960229122813 | | 2011 | 40.076953806783 | | 2010 | 45.145314794996 | | 2009 | 48.471025862554 | | 2008 | 40.889175360198 | | 1998 | 30.296627995094 | | 1997 | 44.293288717441 | | 1996 | 37.920750144417 | | 1995 | 35.841400764895 | | 1994 | 44.017505710522 | | 1993 | 33.698223256241 | | 1992 | 34.01727506201 | | 1991 | 32.129911132363 | | 1990 | 30.245494201652 |
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