1911    20.660
1912    23.980
1913    18.700
1914    16.400
1915    20.320
1916    22.340
1917    26.740
1918    32.860
1919    17.060
1920    25.740
1921    19.920
1922    17.880
1923    16.160
1924    15.400
1925    10.980
1926    14.960
1927    15.140
1928    11.740
1929    26.500
1930     9.460
1931    26.160
1932    35.020
1933    25.740
1934    30.900
1935    16.380
1936    31.640
1937    34.640
1938    12.920
1939     8.640
1940    23.200
1941    16.760
1942    15.600
1943    13.220
1944    14.080
1945     7.900
1946     7.860
1947     8.580
1948    13.980
1949    36.780
1950    28.340
1951    13.060
1952    21.480
1953    18.780
1954    24.920
1955    15.700
1956    16.820
1957    21.120
1958    19.740
1959    16.200
1960    11.820
1961    16.760
1962    11.160
1963    22.540
1964    24.020
1965    14.100
1966    13.320
1967    11.320
1968     8.300
1969    18.180
1970    17.500
1971    10.260
1972    10.700
1973    17.040
1974    15.040
1975    11.200
1976    15.980
1977    31.160
1978    36.720
1979    41.480
1980    12.280
1981    28.280
1982    14.420
1983    30.100
1984    20.060
1985    17.720
1986    15.620
1987    21.120
1988     8.980
1989    11.420
1990    13.420
1991    15.540
1992    31.560
1993    23.860
1994    14.460
1995    19.300
1996    20.180
1997    18.000
1998    30.860
1999    31.100
2000    30.700
2001    13.600
2002    27.520
2003    22.440
2004    11.060
2005    25.660
2006    24.000
2007    15.800
2008    14.840
2009    17.380
2010    25.820
2011    16.280
2012    32.400
2013    17.940