Year | Value | 2022 | 13.477535315838 | 2021 | 13.363401718592 | 2020 | 10.997971301816 | 2019 | 14.239872183026 | 2018 | 15.402360340957 | 2017 | 15.687272676287 | 2016 | 13.50023092971 | 2015 | 13.358079290429 | 2014 | 9.5431839864464 | 2013 | 11.415131480099 | 2012 | 12.448041864867 | 2011 | 16.720794843131 | 2010 | 13.350683028598 | 2009 | 16.182847777603 | 2008 | 14.192562179253 | 2007 | 13.161970672462 | 2006 | 17.154524393286 | 2005 | 17.21594016672 | 2004 | 17.290512547407 | 2003 | 18.11422144917 | 2002 | 17.495261250644 | 2001 | 15.845765675023 | 2000 | 16.199677188492 | 1999 | 17.827699072347 | 1998 | 25.024421584836 | 1997 | 17.599074921914 | 1996 | 19.381275579809 | 1995 | 21.185053966186 | 1994 | 25.957351212972 | 1993 | 24.776927549713 | 1992 | 18.556227384036 | 1991 | 17.157166584857 | 1990 | 23.096056073581 | 1989 | 26.336990956125 | 1988 | 24.59943735348 | 1987 | 25.763646962657 | 1986 | 26.906020918516 | 1985 | 23.217273869302 | 1984 | 23.41769902012 | 1983 | 19.983916968741 | 1982 | 21.998518445142 | 1981 | 22.520378040262 | 1980 | 22.474802187962 | 1979 | 23.414215414973 | 1978 | 18.303971060937 | 1977 | 19.359077955974 | 1976 | 16.627874963523 |
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