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         1182        444 
1994         1490        556 
1995         2420        854 
1996         2673        948 
1997         2554        872 
1998        24044       8590 
1999        12918       4924 
2000        36582      15029 
2001        41621      16353 
2002        35188      15060 
2003        57405      23508 
2004        45180      17207 
2005       304374     137081 
2006       331510     147977 
2007       192740      59670 
2008       109269      31147 
2009        89875      25126 
2010       137732      36671 
2011       145048      39461 
2012       172798      37601 
2013       227899      57426 
2014       475556     118048 
2015       715644     187241 
2016       603533     155993 
2017       510718     138906 
2018       304716      86151 
2019       809223     198315 
2020       532834     135174 
2021       720847     168973 
2022       559783     160500 
2023       513913     147206 
2024       554607     159404 
2025       528526     149967 
2026       354219      83537