| Year | Value | | 2022 | 0.11277263977947 | | 2021 | 1.0754499569643 | | 2020 | 0.53062655953035 | | 2019 | 0.61187594576434 | | 2018 | 0.75590468907625 | | 2017 | 0.37882472632783 | | 2016 | 0.41530672565683 | | 2015 | 0.45678230624613 | | 2014 | 0.50836983095976 | | 2013 | 0.54383044068678 | | 2012 | 0.75174990921056 | | 2011 | 0.92075693306276 | | 2010 | 0.90438198125975 | | 2009 | 0.96563456681352 | | 2008 | 1.025608394685 | | 2007 | 1.0410723624717 | | 2006 | 0.99554308359475 | | 2005 | 0.93675288682243 | | 2004 | 0.96537780018738 | | 2003 | 1.0021095272823 | | 2002 | 1.0014655503007 | | 2001 | 0.76348807811628 | | 2000 | 0.56592463832472 | | 1999 | 0.58882491139916 | | 1998 | 0.60348866419944 | | 1997 | 0.68866951973823 | | 1996 | 0.7941613809091 | | 1995 | 0.91645368836882 | | 1994 | 1.0387746178513 | | 1993 | 1.134870369965 | | 1992 | 1.1863994960791 | | 1991 | 1.2276166000131 | | 1990 | 1.24886002037 | | 1989 | 1.2844448753253 | | 1988 | 1.3601113006547 | | 1987 | 1.3944730192219 | | 1986 | 1.3925228503804 | | 1985 | 1.3750354884295 | | 1984 | 1.3582706739397 | | 1983 | 1.4129419382649 | | 1982 | 1.565653597833 | | 1981 | 1.6938115256983 | | 1980 | 1.7773740614297 | | 1979 | 1.8255818709252 | | 1978 | 1.7902429655619 | | 1977 | 1.773390958773 | | 1976 | 1.7938073147711 | | 1975 | 1.8064495822837 | | 1974 | 1.8696112385707 | | 1973 | 1.9574164398654 | | 1972 | 2.0322565944789 | | 1971 | 2.1234479197323 | | 1970 | 2.1998786929394 | | 1969 | 2.2732494374701 | | 1968 | 2.3556395805397 | | 1967 | 2.3724624129594 | | 1966 | 2.368569659684 | | 1965 | 2.3948532145354 | | 1964 | 2.4100322459105 | | 1963 | 2.4102089889014 | | 1962 | 2.4070116376501 | | 1961 | 2.413606417473 |
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