# year    value 
 1901 10.48024 
 1902 10.07494 
 1903 11.39617 
 1904 9.966746 
 1905 10.06388 
 1906 11.47379 
 1907 11.98915 
 1908 9.688132 
 1909 10.78008 
 1910 10.18578 
 1911 12.10667 
 1912 8.385479 
 1913 11.83359 
 1914 10.11762 
 1915 8.885056 
 1916 10.60293 
 1917 11.16998 
 1918 10.60687 
 1919 9.985133 
 1920 10.04384 
 1921 11.09561 
 1922 9.028534 
 1923 11.80928 
 1924 11.15532 
 1925 10.20365 
 1926 13.06028 
 1927 11.37528 
 1928  11.6272 
 1929 12.30953 
 1930 11.95158 
 1931 9.803274 
 1932 12.36387 
 1933 10.97424 
 1934 11.63802 
 1935 11.78129 
 1936 9.871477 
 1937 11.05022 
 1938 11.92151 
 1939  11.0193 
 1940 11.45871 
 1941 9.768984 
 1942   12.515 
 1943 11.87756 
 1944 10.74758 
 1945 11.09871 
 1946 11.12077 
 1947 12.51938 
 1948 11.67346 
 1949 12.61909 
 1950 11.11553 
 1951 12.13145 
 1952 9.934625 
 1953   11.866 
 1954 11.54871 
 1955 10.72489 
 1956 10.61088 
 1957 11.27199 
 1958 11.93486 
 1959 11.02624 
 1960 11.55922 
 1961 12.75481 
 1962 11.07541 
 1963 12.46587 
 1964 11.41732 
 1965  10.5952 
 1966 11.88828 
 1967 12.16937 
 1968 11.61145 
 1969 12.10756 
 1970 11.81369 
 1971 10.55139 
 1972 9.844452 
 1973 10.96711 
 1974 10.02678 
 1975 11.36397 
 1976 11.24672 
 1977 11.30834 
 1978 10.38745 
 1979 11.28209 
 1980 10.86704 
 1981 11.49534 
 1982  12.7279 
 1983 11.25758 
 1984  11.7775 
 1985 11.17221 
 1986 11.85317 
 1987 12.81745 
 1988  10.9615 
 1989 11.22256 
 1990 11.67921 
 1991 11.69003 
 1992 11.66129 
 1993 10.49323 
 1994   12.407 
 1995 11.39552 
 1996  11.0128 
 1997 11.85337 
 1998 10.78817 
 1999 12.06584 
 2000 12.90624 
 2001 11.46558 
 2002 12.08388 
 2003 11.56271 
 2004 12.40518 
 2005 12.12593 
 2006  13.9481 
 2007 10.65642 
 2008 11.80182 
 2009 12.83851 
 2010 11.34803 
 2011 12.81173 
 2012 12.88909 
 2013 12.50316 
 2014  13.6835 
 2015 12.33953 
 2016 12.35764 
 2017 11.67834 
 2018 13.64148