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        36642      15053 
2001        41704      16385 
2002        35259      15090 
2003        57539      23548 
2004        45336      17257 
2005       304870     137264 
2006       332112     148203 
2007       193117      59770 
2008       109668      31253 
2009        90271      25231 
2010       138351      36831 
2011       145810      39657 
2012       173624      37819 
2013       229341      57793 
2014       477149     118486 
2015       719371     188260 
2016       607592     157152 
2017       515125     140136 
2018       306523      86669 
2019       811091     198800 
2020       533932     135467 
2021       723036     169619 
2022       561848     161100 
2023       514862     147483 
2024       555517     159662 
2025       530256     150397 
2026       297791      66916