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         1198        450 
1994         1528        569 
1995         2496        880 
1996         2737        970 
1997         2626        896 
1998        24116       8607 
1999        12949       4936 
2000        36640      15052 
2001        41694      16381 
2002        35247      15084 
2003        57533      23546 
2004        45325      17253 
2005       304705     137189 
2006       331864     148102 
2007       193105      59767 
2008       109653      31249 
2009        90265      25229 
2010       138339      36828 
2011       145779      39649 
2012       173600      37812 
2013       229256      57784 
2014       477000     118447 
2015       719123     188198 
2016       607464     157119 
2017       515058     140118 
2018       306467      86653 
2019       811016     198780 
2020       533845     135457 
2021       722995     169608 
2022       561793     161084 
2023       514832     147474 
2024       555447     159642 
2025       530128     150361 
2026       301352      67990