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         3099       1081 
1996         2986       1055 
1997         1890        652 
1998        22330       9436 
1999        13595       5217 
2000        38793      16043 
2001        39574      15376 
2002        30978      13878 
2003        58073      24159 
2004        46611      17884 
2005        81959      25222 
2006       105607      33885 
2007       192982      59605 
2008       114508      32740 
2009        94451      26610 
2010       116108      32142 
2011       160672      44549 
2012       154739      43026 
2013       227660      64983 
2014       571965     145953 
2015       801653     210026 
2016       671431     174430 
2017       562475     152279 
2018       361468     101654 
2019       874617     213669 
2020       625500     159267 
2021       844367     200825 
2022       629448     180166 
2023       565431     161713 
2024       631761     181883 
2025       151621      42934