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         1308        487 
1994         1686        619 
1995         3108       1084 
1996         2993       1058 
1997         1917        661 
1998        22337       9439 
1999        13620       5227 
2000        38856      16071 
2001        39640      15406 
2002        31041      13908 
2003        58211      24214 
2004        46723      17930 
2005        82127      25273 
2006       105867      33960 
2007       193477      59738 
2008       115212      32924 
2009        94932      26742 
2010       114144      31688 
2011       161484      44770 
2012       152773      42322 
2013       225385      64191 
2014       568943     145002 
2015       796991     208716 
2016       664280     172278 
2017       560416     151562 
2018       358368     100637 
2019       875325     213734 
2020       628018     159953 
2021       847745     201724 
2022       631757     180839 
2023       569440     162724 
2024       634395     182648 
2025       124922      35663