1955 -11.8957 2.92573 1956 -9.92088 2.91269 1957 -10.7582 2.88561 1958 -5.6893 2.87154 1959 -8.50002 2.89194 1960 -5.52301 2.86612 1961 -4.02085 2.86452 1962 -2.58819 2.84998 1963 -3.96601 2.83704 1964 -4.4649 2.82216 1965 -4.02061 2.79833 1966 -3.33301 2.78786 1967 -5.32107 2.7613 1968 -8.26327 2.72559 1969 -7.39423 2.72234 1970 -5.0594 2.70578 1971 -2.89683 2.65972 1972 -2.7527 2.66807 1973 -1.30943 2.6711 1974 -2.12101 2.70558 1975 1.13674 2.72054 1976 0.248988 2.68993 1977 0.699838 2.68618 1978 -0.508944 2.68008 1979 -1.1342 2.65441 1980 5.18664 2.64385 1981 5.73512 2.64665 1982 3.67745 2.6369 1983 1.80658 2.62844 1984 4.06679 2.64215 1985 5.01641 2.61358 1986 5.28403 2.61458 1987 4.44015 2.5882 1988 7.50848 2.60034 1989 6.90981 2.61057 1990 7.43767 2.55763 1991 9.45791 2.56311 1992 9.04616 2.55419 1993 7.46389 2.54345 1994 9.01314 2.57398 1995 7.85502 2.55072 1996 11.355 2.55389 1997 12.4248 2.54786 1998 10.5271 2.53651 1999 13.3607 2.54672 2000 12.3419 2.56222 2001 16.6186 2.57552 2002 20.3811 2.56577 2003 23.8117 2.50258 2004 22.7469 2.42438 2005 22.8266 2.37615 2006 23.1829 2.37011 2007 21.7734 2.35808 2008 24.2105 2.36104 2009 25.8839 2.35565 2010 25.858 2.35335 2011 26.7622 2.35469 2012 27.7749 2.35524 2013 30.3794 2.40358 2014 31.9525 2.40934 2015 34.0514 2.3962 2016 32.7057 2.39047 2017 35.7593 2.29992 2018 34.5527 2.41992