Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          471        179 
1992          749        303 
1993         1313        489 
1994         1692        621 
1995         3117       1087 
1996         3008       1063 
1997         1961        676 
1998        22355       9446 
1999        13636       5233 
2000        38960      16118 
2001        39728      15445 
2002        31176      13968 
2003        58428      24303 
2004        46921      18007 
2005        82518      25391 
2006       106245      34071 
2007       194335      59972 
2008       116211      33193 
2009        95731      26963 
2010       110470      30812 
2011       162882      45149 
2012       154176      42708 
2013       227086      64659 
2014       562357     143554 
2015       778717     204178 
2016       664353     172355 
2017       563931     152463 
2018       361556     101525 
2019       879958     214890 
2020       632992     161296 
2021       853303     203196 
2022       635148     181815 
2023       571075     163509 
2024       640488     184459 
2025        54103      15447