The stations with long time service used
Year | Number of stations | Yearly mean |
---|---|---|
1910 | 9 | 19.15 |
1911 | 11 | 19.84 |
1912 | 8 | 19.96 |
1913 | 12 | 19.17 |
1914 | 10 | 21.33 |
1915 | 13 | 21.31 |
1916 | 10 | 20.23 |
1917 | 10 | 19.34 |
1918 | 14 | 19.98 |
1919 | 13 | 20.33 |
1920 | 13 | 19.14 |
1921 | 15 | 20.26 |
1922 | 14 | 20.20 |
1923 | 16 | 20.36 |
1924 | 11 | 19.60 |
1925 | 13 | 19.53 |
1926 | 15 | 20.72 |
1927 | 10 | 19.76 |
1928 | 13 | 21.13 |
1929 | 11 | 18.72 |
1930 | 13 | 20.33 |
1931 | 13 | 20.79 |
1932 | 11 | 19.61 |
1933 | 10 | 19.61 |
1934 | 11 | 19.65 |
1935 | 13 | 19.51 |
1936 | 11 | 19.16 |
1937 | 12 | 19.55 |
1938 | 10 | 19.51 |
1939 | 10 | 18.71 |
1940 | 15 | 20.10 |
1941 | 15 | 20.50 |
1942 | 18 | 22.24 |
1943 | 15 | 20.72 |
1944 | 19 | 21.54 |
1945 | 20 | 20.84 |
1946 | 18 | 20.73 |
1947 | 20 | 20.86 |
1948 | 19 | 21.84 |
1949 | 21 | 20.44 |
1950 | 19 | 21.30 |
1951 | 19 | 20.64 |
1952 | 17 | 20.61 |
1953 | 22 | 21.09 |
1954 | 21 | 21.29 |
1955 | 20 | 20.83 |
1956 | 19 | 20.43 |
1957 | 18 | 21.78 |
1958 | 21 | 22.36 |
1959 | 19 | 21.20 |
1960 | 12 | 20.88 |
1961 | 15 | 21.96 |
1962 | 19 | 21.61 |
1963 | 22 | 21.43 |
1964 | 20 | 21.60 |
1965 | 22 | 21.54 |
1966 | 20 | 21.78 |
1967 | 22 | 21.38 |
1968 | 19 | 21.19 |
1969 | 20 | 21.03 |
1970 | 14 | 22.57 |
1971 | 21 | 20.45 |
1972 | 19 | 21.41 |
1973 | 14 | 21.14 |
1974 | 18 | 21.26 |
1975 | 19 | 21.44 |
1976 | 17 | 19.38 |
1977 | 19 | 20.39 |
1978 | 19 | 20.27 |
1979 | 19 | 20.87 |
1980 | 19 | 21.48 |
1981 | 21 | 21.56 |
1982 | 15 | 21.03 |
1983 | 15 | 20.94 |
1984 | 17 | 19.83 |
1985 | 15 | 19.97 |
1986 | 15 | 20.71 |
1987 | 20 | 21.08 |
1988 | 18 | 21.80 |
1989 | 17 | 20.51 |
1990 | 19 | 21.49 |
1991 | 19 | 20.91 |
1992 | 22 | 20.78 |
1993 | 19 | 20.87 |
1994 | 18 | 20.88 |
1995 | 20 | 20.91 |
1996 | 19 | 21.03 |
1997 | 18 | 20.29 |
1998 | 19 | 20.93 |
1999 | 19 | 20.93 |
2000 | 22 | 20.66 |
2001 | 21 | 20.25 |
2002 | 22 | 21.23 |
2003 | 18 | 20.95 |
2004 | 22 | 20.80 |
2005 | 21 | 21.56 |
2006 | 20 | 20.37 |
2007 | 21 | 20.89 |
2008 | 20 | 21.74 |
2009 | 20 | 21.17 |
2010 | 20 | 21.18 |
2011 | 16 | 19.62 |
2012 | 14 | 21.63 |
2013 | 13 | 22.97 |