Year | Value | 2022 | 29.947491987303 | 2021 | 28.181403643948 | 2020 | 28.507688200732 | 2019 | 29.702200578672 | 2018 | 31.410492230486 | 2017 | 31.706753170878 | 2016 | 31.726414740149 | 2015 | 32.453924110913 | 2014 | 33.466025744283 | 2013 | 34.304657487069 | 2012 | 35.261292313665 | 2011 | 35.131793094081 | 2010 | 36.305875040972 | 2009 | 35.617434813018 | 2008 | 36.254082632816 | 2007 | 37.011389004128 | 2006 | 36.360532109845 | 2005 | 34.418022902624 | 2004 | 33.332571242167 | 2003 | 30.470966542202 | 2002 | 28.111485574288 | 2001 | 26.259879026634 | 2000 | 26.119027312104 | 1999 | 25.637536503504 | 1998 | 25.889504645606 | 1997 | 27.550434015696 | 1996 | 27.047935038253 | 1995 | 26.967391093045 | 1994 | 25.951000890711 | 1993 | 24.083079277442 | 1992 | 23.246801620775 | 1991 | 21.75996609665 | 1990 | 21.213563235422 | 1989 | 20.144439587408 | 1988 | 18.156809131376 | 1987 | 16.982525103495 | 1986 | 15.788506028959 | 1985 | 16.798311291609 | 1984 | 15.795566949476 | 1983 | 15.354749508293 | 1982 | 15.805984915272 | 1981 | 15.80787417028 | 1980 | 14.525756135773 | 1979 | 15.768987486409 | 1978 | 15.058256724516 | 1977 | 15.404981368212 | 1976 | 15.965598075525 | 1975 | 13.098093003731 |
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