Graph
Year | Totals | Observation hours |
---|---|---|
1953 | 0 | 51:15 |
1954 | 5 | 64:45 |
1955 | 0 | 81:45 |
1956 | 2 | 80:00 |
1957 | 18 | 99:45 |
1958 | 8 | 84:00 |
1959 | 0 | 77:00 |
1960 | 3 | 68:45 |
1961 | 16 | 84:30 |
1962 | 0 | 69:30 |
1963 | 4 | 53:30 |
1964 | 1 | 53:15 |
1965 | 0 | 68:30 |
1966 | 0 | 48:45 |
1967 | 0 | 31:00 |
1968 | 5 | 33:15 |
1969 | 2 | 36:15 |
1970 | 15 | 50:30 |
1971 | 12 | 38:15 |
1972 | 2 | 45:45 |
1973 | 6 | 27:15 |
1974 | 0 | 0:00 |
1975 | 3 | 55:15 |
1976 | 3 | 48:00 |
1977 | 16 | 43:15 |
1978 | 2 | 45:00 |
1979 | 5 | 52:00 |
1980 | 56 | 51:45 |
1981 | 20 | 62:00 |
1982 | 269 | 177:30 |
1983 | 0 | 4:15 |
1984 | 285 | 194:00 |
1985 | 814 | 253:45 |
1986 | 122 | 292:00 |
1987 | 242 | 287:15 |
1988 | 523 | 376:10 |
1989 | 678 | 239:42 |
1990 | 355 | 134:45 |
1991 | 202 | 128:00 |
1992 | 172 | 116:30 |
1993 | 35 | 117:45 |
1994 | 2 | 67:00 |
1995 | 10 | 90:30 |
1996 | 2 | 102:10 |
1997 | 2 | 89:00 |
1998 | 0 | 49:45 |
1999 | 49 | 162:00 |
2000 | 34 | 123:30 |
2001 | 196 | 185:15 |
2002 | 143 | 143:15 |
2003 | 23 | 85:30 |
2004 | 19 | 106:30 |
2005 | 7 | 112:30 |
2006 | 2 | 60:00 |
2007 | 6 | 70:30 |
2008 | 10 | 103:51 |
2009 | 118 | 78:30 |
2010 | 28 | 76:30 |
2011 | 109 | 214:15 |
2012 | 134 | 225:50 |
2013 | 391 | 180:30 |
2014 | 201 | 206:35 |
2015 | 25 | 77:15 |
2016 | 53 | 101:05 |
2017 | 22 | 55:40 |
2018 | 13 | 66:31 |
2019 | 32 | 90:45 |
2020 | 323 | 172:21 |
2021 | 0 | 7:30 |