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          659        271 
1993         1187        446 
1994         1505        561 
1995         2450        864 
1996         2705        959 
1997         2590        884 
1998        24080       8595 
1999        12925       4927 
2000        36610      15041 
2001        41657      16367 
2002        35208      15069 
2003        57459      23526 
2004        45256      17231 
2005       304559     137144 
2006       331716     148052 
2007       192887      59709 
2008       109460      31199 
2009        90064      25175 
2010       138017      36745 
2011       145380      39545 
2012       173168      37698 
2013       228503      57583 
2014       476210     118229 
2015       716731     187586 
2016       604949     156404 
2017       512421     139403 
2018       305560      86392 
2019       810093     198542 
2020       533340     135314 
2021       721847     169270 
2022       560804     160792 
2023       514443     147361 
2024       554999     159511 
2025       529147     150128 
2026       343060      79205