1910    21.160
1911    16.940
1912    24.800
1913    20.140
1914    20.940
1915    36.960
1916    19.840
1917    22.940
1918    16.660
1919    21.960
1920    17.560
1921    18.480
1922    12.940
1923    16.960
1924    22.840
1925    18.520
1926    14.380
1927    26.440
1928    21.200
1929    14.240
1930    19.180
1931    24.060
1932    11.540
1933    20.300
1934    34.520
1935    10.320
1936    36.940
1937    14.960
1938    10.380
1939    10.160
1940    17.920
1941    21.420
1942    13.300
1943    20.200
1944    18.300
1945    17.280
1946    12.140
1947    13.800
1948    10.540
1949    17.300
1950    24.740
1951    23.160
1952    17.280
1953    19.960
1954    28.800
1955    15.740
1956    15.640
1957    11.280
1958    19.200
1959    12.100
1960    11.620
1961    25.580
1962     9.440
1963    15.040
1964    13.660
1965    18.080
1966    11.920
1967    24.940
1968    10.620
1969     6.540
1970    10.980
1971     7.140
1972    15.000
1973    16.300
1974    14.500
1975    15.060
1976    23.540
1977    12.440
1978    11.340
1979    15.140
1980    25.480
1981    14.620
1982    13.760
1983    26.820
1984    17.060
1985    15.220
1986    11.340
1987    13.140
1988    27.920
1989    18.380
1990    11.800
1991    16.120
1992    35.920
1993    32.840
1994    18.620
1995    19.780
1996    17.380
1997    15.420
1998    22.640
1999    16.020
2000    19.660
2001    16.660
2002    27.560
2003    26.140
2004    27.700
2005    21.620
2006    27.040
2007    33.920
2008    18.840
2009    23.060
2010    29.240
2011    38.940
2012    32.400