1900	24.42
1901	20.99
1902	21.41
1903	22.82
1904	15.94
1905	16.93
1906	26.18
1907	19.42
1908	22.55
1909	25.15
1910	21.54
1911	21.34
1912	20.69
1913	27.10
1914	21.83
1915	24.26
1916	23.15
1917	21.12
1918	15.75
1919	27.62
1920	17.20
1921	26.43
1922	22.52
1923	20.51
1924	24.93
1925	23.48
1926	22.64
1927	22.69
1928	24.85
1929	24.59
1930	24.82
1931	24.27
1932	30.47
1933	29.38
1934	18.86
1935	21.28
1936	18.81
1937	28.80
1938	24.29
1939	24.93
1940	21.10
1941	23.43
1942	23.39
1943	21.32
1944	23.49
1945	19.70
1946	22.06
1947	24.87
1948	19.78
1949	28.70
1950	27.51
1951	25.31
1952	26.59
1953	28.82
1954	27.42
1955	23.24
1956	22.76
1957	25.03
1958	23.72
1959	19.49
1960	25.94
1961	20.60
1962	22.73
1963	19.52
1964	21.78
1965	22.98
1966	24.31
1967	24.48
1968	20.94
1969	22.66
1970	19.08
1971	21.30
1972	24.48
1973	24.79
1974	24.25
1975	27.08
1976	23.46
1977	18.69
1978	19.47
1979	20.16
1980	24.43
1981	21.95
1982	21.22
1983	27.98
1984	24.23
1985	25.10
1986	22.54
1987	24.05
1988	24.77
1989	25.08
1990	24.17
1991	27.93
1992	26.10
1993	23.56
1994	18.89
1995	26.59
1996	21.67
1997	27.68
1998	29.42
1999	27.82