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         1310        488 
1994         1689        620 
1995         3111       1085 
1996         2993       1058 
1997         1917        661 
1998        22337       9439 
1999        13620       5227 
2000        38858      16072 
2001        39646      15409 
2002        31043      13909 
2003        58223      24218 
2004        46742      17937 
2005        82155      25281 
2006       105885      33966 
2007       193544      59757 
2008       115285      32943 
2009        95009      26762 
2010       114168      31694 
2011       161596      44801 
2012       152889      42354 
2013       225523      64227 
2014       568764     144973 
2015       796015     208448 
2016       664359     172301 
2017       560549     151600 
2018       358602     100701 
2019       875682     213802 
2020       628462     160053 
2021       848271     201852 
2022       631962     180897 
2023       569843     162830 
2024       635063     182836 
2025       125848      35904