Year Dollars 1914 19.1800 1915 18.9100 1916 19.5800 1917 21.0700 1918 24.1100 1919 27.1300 1920 31.0600 1921 31.2700 1922 31.2000 1923 32.5600 1924 33.5800 1925 34.4900 1926 35.3800 1927 35.8800 1928 36.3700 1929 36.9400 1930 37.4800 1931 35.4900 1932 31.8600 1933 31.8500 1934 32.4500 1935 32.7100 1936 33.0500 1937 33.9300 1938 34.1900