1910    21.320
1911    24.860
1912    21.980
1913    11.240
1914    19.260
1915    19.980
1916    23.140
1917    29.500
1918    10.780
1919    27.920
1920    13.480
1921    19.300
1922    15.540
1923    17.260
1924    18.120
1925    20.460
1926    15.500
1927    24.880
1928     9.260
1929    25.960
1930    15.600
1931    36.380
1932    21.460
1933    26.940
1934    18.120
1935    11.920
1936    20.080
1937    20.880
1938    18.520
1939    22.140
1940    12.540
1941    30.060
1942    10.240
1943    19.300
1944     8.660
1945    10.380
1946    20.040
1947    14.440
1948    13.560
1949     8.220
1950    18.840
1951    19.940
1952    29.620
1953    34.680
1954    23.840
1955    15.620
1956    21.180
1957    20.920
1958    11.400
1959    21.860
1960     7.680
1961    21.480
1962    11.880
1963    38.480
1964    13.080
1965    11.660
1966     7.900
1967    18.700
1968     7.920
1969     6.100
1970    12.040
1971    18.500
1972    24.640
1973    24.840
1974    16.860
1975    10.300
1976    33.460
1977    15.320
1978    11.500
1979    15.600
1980    10.200
1981    12.800
1982    15.340
1983    19.380
1984    16.660
1985    38.420
1986    24.240
1987    15.940
1988    14.260
1989    13.980
1990    18.580
1991    17.460
1992    13.140
1993    24.320
1994    14.500
1995    23.220
1996    23.720
1997    12.780
1998    33.900
1999    27.620
2000    10.740
2001    24.780
2002    18.680
2003    17.120
2004    27.800
2005    25.820
2006    12.060
2007    24.520
2008    17.900
2009    19.820
2010    18.380
2011    22.780
2012    23.160