1910    20.580
1911    27.520
1912    30.180
1913    20.880
1914    20.480
1915    20.840
1916    23.740
1917    34.640
1918    15.000
1919     8.320
1920    22.840
1921    25.740
1922    23.460
1923    12.700
1924    27.220
1925    22.220
1926    22.560
1927    21.800
1928    11.380
1929    29.480
1930     7.460
1931    23.880
1932    12.640
1933    19.820
1934    38.720
1935    14.080
1936    21.240
1937    26.120
1938    20.500
1939     8.660
1940    31.520
1941    22.140
1942    17.660
1943    14.900
1944    11.240
1945    10.580
1946    17.840
1947    14.700
1948    13.960
1949    22.440
1950    24.020
1951    12.160
1952    11.080
1953    14.920
1954    20.700
1955    23.420
1956    12.920
1957    17.340
1958    24.880
1959    10.200
1960    18.560
1961    11.000
1962     6.500
1963    10.800
1964    20.260
1965    12.000
1966    15.240
1967     9.440
1968    12.280
1969    11.540
1970    10.740
1971    14.860
1972    15.820
1973    24.260
1974    19.420
1975    18.060
1976    11.440
1977    15.540
1978    32.100
1979    34.240
1980    15.200
1981    21.620
1982    12.920
1983    27.720
1984    18.100
1985    14.440
1986    26.380
1987    25.760
1988    15.040
1989    12.060
1990    26.660
1991    22.980
1992    31.180
1993    22.460
1994    16.440
1995    15.860
1996    28.300
1997    18.860
1998    30.680
1999    22.740
2000    39.160
2001    13.540
2002    20.380
2003    18.160
2004    18.380
2005    19.020
2006    36.500
2007    21.600
2008    16.960
2009    16.060
2010    20.380
2011    25.700
2012    43.800
2013    20.320