Year MBBl 1880 30 1890 77 1900 149 1905 215 1910 328 1915 432 1920 689 1925 1069 1930 1412 1935 1655 1940 2150 1945 2595 1950 3803 1955 5626 1960 7674 1962 8882 1964 10310 1966 12016 1968 14104 1970 16690 1972 18584 1974 20389 1976 20188 1978 21922 1980 21722 1982 19411 1984 19837 1986 20246 1988 21338