Graph
Year | Totals | Observation hours |
---|---|---|
1953 | 0 | 51:15 |
1954 | 2 | 64:45 |
1955 | 2 | 81:45 |
1956 | 35 | 80:00 |
1957 | 6 | 99:45 |
1958 | 0 | 84:00 |
1959 | 11 | 77:00 |
1960 | 3 | 68:45 |
1961 | 9 | 84:30 |
1962 | 8 | 69:30 |
1963 | 0 | 53:30 |
1964 | 1 | 53:15 |
1965 | 2 | 68:30 |
1966 | 4 | 48:45 |
1967 | 1 | 31:00 |
1968 | 2 | 33:15 |
1969 | 1 | 36:15 |
1970 | 1 | 50:30 |
1971 | 0 | 38:15 |
1972 | 4 | 45:45 |
1973 | 0 | 27:15 |
1974 | 0 | 0:00 |
1975 | 1 | 55:15 |
1976 | 7 | 48:00 |
1977 | 2 | 43:15 |
1978 | 2 | 45:00 |
1979 | 7 | 52:00 |
1980 | 19 | 51:45 |
1981 | 69 | 62:00 |
1982 | 72 | 177:30 |
1983 | 0 | 4:15 |
1984 | 50 | 194:00 |
1985 | 106 | 253:45 |
1986 | 79 | 292:00 |
1987 | 246 | 287:15 |
1988 | 148 | 376:10 |
1989 | 120 | 239:42 |
1990 | 168 | 134:45 |
1991 | 68 | 128:00 |
1992 | 89 | 116:30 |
1993 | 39 | 117:45 |
1994 | 48 | 67:00 |
1995 | 33 | 90:30 |
1996 | 25 | 102:10 |
1997 | 16 | 89:00 |
1998 | 11 | 49:45 |
1999 | 95 | 162:00 |
2000 | 50 | 123:30 |
2001 | 76 | 185:15 |
2002 | 54 | 143:15 |
2003 | 35 | 85:30 |
2004 | 71 | 106:30 |
2005 | 54 | 112:30 |
2006 | 46 | 60:00 |
2007 | 62 | 70:30 |
2008 | 93 | 103:51 |
2009 | 21 | 78:30 |
2010 | 66 | 76:30 |
2011 | 113 | 214:15 |
2012 | 161 | 225:50 |
2013 | 200 | 180:30 |
2014 | 148 | 206:35 |
2015 | 56 | 77:15 |
2016 | 53 | 101:05 |
2017 | 28 | 55:40 |
2018 | 40 | 66:31 |
2019 | 103 | 90:45 |
2020 | 312 | 172:21 |
2021 | 65 | 142:00 |
2022 | 84 | 36:27 |