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         1192        448 
1994         1514        564 
1995         2465        869 
1996         2714        962 
1997         2599        887 
1998        24089       8598 
1999        12935       4931 
2000        36614      15042 
2001        41660      16368 
2002        35219      15073 
2003        57459      23526 
2004        45262      17233 
2005       304573     137148 
2006       331752     148063 
2007       192926      59719 
2008       109489      31207 
2009        90078      25179 
2010       138074      36760 
2011       145470      39565 
2012       173254      37721 
2013       228648      57622 
2014       476384     118280 
2015       717070     187687 
2016       605494     156561 
2017       513053     139586 
2018       305749      86446 
2019       810187     198568 
2020       533392     135328 
2021       721931     169299 
2022       560885     160816 
2023       514472     147370 
2024       555056     159527 
2025       529188     150139 
2026       335220      77012