1910    33.900
1911    19.560
1912    23.420
1913    15.220
1914    18.260
1915    23.320
1916    18.360
1917    34.180
1918    18.860
1919     8.040
1920    22.620
1921    18.980
1922    18.160
1923    17.960
1924    27.780
1925    23.360
1926    32.920
1927    18.020
1928    14.060
1929    17.220
1930     7.960
1931    26.880
1932    11.840
1933    12.800
1934    38.640
1935    18.540
1936    15.500
1937     9.520
1938    16.420
1939    13.620
1940    21.800
1941    25.120
1942    17.220
1943    15.080
1944    12.900
1945    18.280
1946    17.260
1947    23.220
1948    16.460
1949     6.060
1950    21.340
1951    17.880
1952    11.880
1953    12.200
1954    14.020
1955    28.860
1956    18.980
1957    17.960
1958    19.920
1959     8.940
1960    22.820
1961    12.540
1962     7.200
1963    15.160
1964    17.740
1965    17.080
1966    13.300
1967    19.980
1968     7.480
1969    13.220
1970    11.780
1971    19.120
1972    14.480
1973    26.740
1974    18.320
1975    24.180
1976     9.360
1977    29.620
1978    10.740
1979    13.520
1980    15.900
1981    13.020
1982     8.840
1983    33.500
1984    23.200
1985    23.640
1986    20.180
1987    28.500
1988    16.380
1989    18.720
1990    14.820
1991    31.160
1992    27.400
1993    23.160
1994    17.740
1995    19.080
1996    25.860
1997    19.360
1998    22.480
1999    12.160
2000    27.440
2001    15.940
2002    22.200
2003    15.620
2004    34.220
2005    15.400
2006    24.800
2007    31.620
2008    16.760
2009    14.360
2010    23.320
2011    34.480
2012    44.800