Graph
Year | Totals | Observation hours |
---|---|---|
1960 | 0 | 0:00 |
1961 | 0 | 0:00 |
1962 | 0 | 0:00 |
1963 | 0 | 0:00 |
1964 | 0 | 0:00 |
1965 | 0 | 0:00 |
1966 | 0 | 0:00 |
1967 | 0 | 0:00 |
1968 | 0 | 0:00 |
1969 | 0 | 0:00 |
1970 | 0 | 0:00 |
1971 | 0 | 0:00 |
1972 | 0 | 0:00 |
1973 | 0 | 0:00 |
1974 | 0 | 0:00 |
1975 | 0 | 0:00 |
1976 | 0 | 0:00 |
1977 | 40 | 791:25 |
1978 | 154 | 820:52 |
1979 | 353 | 934:10 |
1980 | 297 | 731:36 |
1981 | 814 | 944:01 |
1982 | 532 | 768:05 |
1983 | 340 | 673:25 |
1984 | 237 | 682:07 |
1985 | 128 | 775:03 |
1986 | 317 | 933:53 |
1987 | 506 | 1120:12 |
1988 | 487 | 1184:32 |
1989 | 817 | 1293:12 |
1990 | 1003 | 944:40 |
1991 | 563 | 858:50 |
1992 | 446 | 759:26 |
1993 | 480 | 827:13 |
1994 | 352 | 1135:36 |
1995 | 709 | 1315:15 |
1996 | 432 | 1503:39 |
1997 | 343 | 1460:20 |
1998 | 542 | 1162:42 |
1999 | 408 | 1225:50 |
2000 | 375 | 1031:40 |
2001 | 331 | 1273:17 |
2002 | 491 | 1125:31 |
2003 | 519 | 1253:15 |
2004 | 548 | 1065:05 |
2005 | 402 | 1106:54 |
2006 | 305 | 964:46 |
2007 | 484 | 1089:29 |
2008 | 608 | 1099:59 |
2009 | 914 | 1282:49 |
2010 | 720 | 1288:05 |
2011 | 600 | 1234:15 |
2012 | 563 | 1364:55 |
2013 | 793 | 1352:29 |
2014 | 497 | 1299:50 |
2015 | 549 | 1223:30 |
2016 | 464 | 1409:54 |
2017 | 33 | 524:40 |
2018 | 484 | 1539:51 |
2019 | 420 | 1131:19 |
2020 | 340 | 1214:00 |
2021 | 337 | 1459:20 |
2022 | 138 | 493:15 |