Year | Value | 2022 | 26.779490023159 | 2021 | 28.217189054188 | 2020 | 27.695851941825 | 2019 | 27.230559607571 | 2018 | 27.320563060223 | 2017 | 28.591984047033 | 2016 | 28.269894011308 | 2015 | 28.258597513341 | 2014 | 25.317806903449 | 2013 | 32.645821242644 | 2012 | 31.312863881476 | 2011 | 33.760040297931 | 2010 | 35.044102995242 | 2009 | 35.510720963081 | 2008 | 40.190307448023 | 2007 | 39.938210742557 | 2006 | 39.923878266754 | 2005 | 38.77852008343 | 2004 | 39.356780875557 | 2003 | 39.228053682905 | 2002 | 37.964113640405 | 2001 | 38.572845830445 | 2000 | 32.427286383075 | 1999 | 32.96727709532 | 1998 | 34.830443302766 | 1997 | 24.761798691576 | 1996 | 24.586807682403 | 1995 | 21.845220710526 | 1994 | 23.762980428434 | 1993 | 24.881158140427 | 1992 | 26.571245139088 | 1991 | 26.15992451227 | 1990 | 30.439600126253 | 1989 | 27.739631170855 | 1988 | 26.986390902305 | 1987 | 25.926478853821 | 1986 | 26.510532968308 | 1985 | 25.261782140021 | 1984 | 25.281725086392 | 1983 | 21.911073485671 | 1982 | 23.486719353566 | 1981 | 22.575232102327 | 1980 | 24.818607204325 | 1979 | 15.788688719983 | 1978 | 16.028639861571 | 1977 | 16.205371064463 | 1976 | 14.832735725279 | 1975 | 19.752460074156 |
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