| Year | Value | | 2022 | 57.417581137104 | | 2021 | 53.911814421305 | | 2020 | 51.562725336583 | | 2019 | 48.960381669303 | | 2018 | 51.487992415972 | | 2017 | 47.959877118962 | | 2016 | 45.714933892384 | | 2015 | 46.31939625397 | | 2014 | 44.024030705902 | | 2013 | 43.040541705383 | | 2012 | 43.682552247 | | 2011 | 44.481232102307 | | 2010 | 43.659469263271 | | 2009 | 44.682078203347 | | 2008 | 44.113411076331 | | 2007 | 46.387332679283 | | 2006 | 47.209978233723 | | 2005 | 48.069668229736 | | 2004 | 50.596757874101 | | 2003 | 47.966894989054 | | 2002 | 46.996289989386 | | 2001 | 46.561742714641 | | 2000 | 44.132796054373 | | 1999 | 45.048513685566 | | 1998 | 44.857762073434 | | 1997 | 48.585108079236 | | 1996 | 52.661333032924 | | 1995 | 51.590189742761 | | 1994 | 49.285609924473 | | 1993 | 47.852860662216 | | 1992 | 42.753324336658 | | 1991 | 39.427977384112 | | 1990 | 42.099353512021 |
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