| Year | Value | | 2022 | 0.24815605524632 | | 2021 | 0.41562167733756 | | 2020 | 2.2047886959456 | | 2019 | 1.5911588961972 | | 2018 | 1.7912401675903 | | 2017 | 2.0887227228194 | | 2016 | 2.2460321001558 | | 2015 | 2.0360339086492 | | 2014 | 1.6610120007115 | | 2013 | 0.76834799819481 | | 2012 | 0.54822079729833 | | 2011 | 0.76247979510522 | | 2010 | 1.1117260560215 | | 2009 | 0.99972803120842 | | 2008 | 0.84870140242259 | | 2007 | 0.93240768751232 | | 2006 | 1.2189848602843 | | 2005 | 1.1287735096799 | | 2004 | 1.4862190824457 | | 2003 | 1.9735585443416 | | 2002 | 1.7371748643442 | | 2001 | 0.58928603496905 | | 2000 | 0.58756408638135 | | 1999 | 0.52548453621322 | | 1998 | 0.88727988863348 | | 1997 | 1.3123582864988 | | 1996 | 1.58266192728 | | 1995 | 1.4643637874618 | | 1994 | 1.3292373349434 | | 1993 | 1.1402311066289 | | 1992 | 1.0417353842218 | | 1990 | 0.92322272881111 | | 1989 | 0.48005439622228 | | 1988 | 0.27448246822247 | | 1987 | 0.86187599324805 | | 1986 | 0.024640404227286 | | 1985 | 0.61783891819161 | | 1984 | 0.86518652475223 | | 1983 | 1.3594947716689 | | 1982 | 0.99348054833669 | | 1981 | 0.3847515086527 | | 1980 | 0.12536365132103 | | 1979 | 0.39164121838523 | | 1978 | 0.032044092945716 | | 1977 | 0.31136173580744 | | 1976 | 0.88479006559375 | | 1975 | 1.9454337270195 | | 1974 | 2.085288593699 | | 1973 | 1.9573700001881 | | 1972 | 1.7683588876572 | | 1971 | 1.4937509588248 | | 1970 | 1.3575922663911 | | 1969 | 0.89478761793131 | | 1968 | 0.87716654669175 | | 1967 | 1.7852325973011 | | 1966 | 1.7910476318387 | | 1965 | 1.6495061173865 | | 1964 | 2.0949722647119 | | 1963 | 1.9865825438175 | | 1962 | 2.5421121240506 | | 1961 | 1.9994404993352 |
|