1918 4.42000 1919 4.01000 1920 4.66000 1921 4.84000 1922 5.10000 1923 4.34000 1924 4.09000 1925 5.09000 1926 3.79000 1927 4.46000 1928 3.68000 1929 4.74000 1930 4.31000 1931 3.30000 1932 4.28000 1933 3.86000 1934 3.87000 1935 3.60000 1936 4.74000 1937 4.27000 1938 4.44000 1939 5.58000 1940 5.56000 1941 6.09000 1942 5.27000 1943 4.79000 1944 5.45000 1945 4.92000 1946 5.94000 1947 6.34000 1948 7.27000 1949 7.30000 1950 7.60000 1951 10.0800