Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           12          6 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          216         77 
1991          856        306 
1992          656        270 
1993         1176        442 
1994         1487        555 
1995         2356        832 
1996         2628        933 
1997         2498        853 
1998        23927       8549 
1999        12843       4898 
2000        36349      14929 
2001        41431      16270 
2002        34991      14972 
2003        56971      23336 
2004        44836      17078 
2005       303105     136582 
2006       330544     147601 
2007       191783      59417 
2008       107814      30759 
2009        88371      24724 
2010       136014      36228 
2011       142951      38899 
2012       170433      36966 
2013       224642      56533 
2014       471885     117100 
2015       710583     185854 
2016       599637     154957 
2017       504498     137162 
2018       301231      85189 
2019       803756     196879 
2020       527269     133612 
2021       710063     166192 
2022       551539     158200 
2023       509778     146049 
2024       549904     158064 
2025       524090     148709 
2026       367392      87396