1911    26.720
1912    33.700
1913    27.240
1914    16.840
1915    21.300
1916    21.300
1917    34.080
1918    31.920
1919    16.820
1920    28.700
1921    24.620
1922    18.740
1923    13.040
1924    16.740
1925    18.060
1926    19.380
1927    14.100
1928    14.500
1929    17.700
1930    14.060
1931    24.860
1932    31.860
1933    15.920
1934    34.400
1935    25.460
1936    22.440
1937    25.740
1938    14.400
1939    13.260
1940    22.260
1941    16.920
1942    21.140
1943    12.880
1944     9.940
1945     9.800
1946    10.440
1947     8.640
1948    15.340
1949    29.600
1950    21.360
1951    19.880
1952    19.980
1953    13.820
1954    24.680
1955    16.180
1956    20.900
1957    14.800
1958    21.620
1959    12.120
1960    21.080
1961    12.280
1962    12.460
1963    12.680
1964    18.400
1965    14.040
1966    11.900
1967    14.020
1968     9.580
1969    16.160
1970    17.040
1971     9.020
1972    11.300
1973    27.940
1974    24.020
1975     9.800
1976    17.140
1977    34.480
1978    32.720
1979    28.680
1980    11.860
1981    28.660
1982    13.060
1983    29.200
1984    20.480
1985    20.460
1986    14.720
1987    19.180
1988    12.140
1989    10.020
1990    15.680
1991    18.400
1992    24.520
1993    21.060
1994    13.420
1995    22.260
1996    30.560
1997    21.760
1998    25.720
1999    35.500
2000    38.400
2001    18.120
2002    27.340
2003    20.220
2004    17.780
2005    29.740
2006    28.800
2007    17.460
2008    19.080
2009    20.460
2010    25.220
2011    17.580
2012    38.980
2013    15.180