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          664        273 
1993         1201        451 
1994         1531        570 
1995         2513        886 
1996         2743        972 
1997         2632        898 
1998        24131       8613 
1999        12955       4938 
2000        36651      15057 
2001        41715      16389 
2002        35267      15093 
2003        57572      23560 
2004        45342      17259 
2005       304915     137282 
2006       332216     148242 
2007       193203      59793 
2008       109814      31292 
2009        90379      25259 
2010       138490      36868 
2011       146027      39718 
2012       173838      37876 
2013       229585      57861 
2014       477593     118606 
2015       721625     188830 
2016       609140     157551 
2017       516168     140391 
2018       306858      86763 
2019       811758     198981 
2020       534388     135592 
2021       723793     169805 
2022       562815     161369 
2023       515477     147655 
2024       556393     159908 
2025       532040     150836 
2026       276746      61235