1919 2.46000 1920 3.22000 1921 2.27000 1922 2.12000 1923 2.47000 1924 2.29000 1925 2.33000 1926 2.40000 1927 2.35000 1928 2.26000 1929 2.33000 1930 2.00000 1931 1.58000 1932 1.12000 1933 1.06000 1934 1.16000 1935 1.27000 1936 1.47000 1937 1.59000 1938 1.35000