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         2989       1056 
1997         1899        655 
1998        22340       9440 
1999        13611       5224 
2000        38835      16061 
2001        39605      15391 
2002        31016      13895 
2003        58168      24198 
2004        46689      17916 
2005        82063      25253 
2006       105746      33924 
2007       193261      59682 
2008       114963      32857 
2009        94747      26692 
2010       113991      31649 
2011       161188      44689 
2012       152491      42244 
2013       224980      64077 
2014       569251     145072 
2015       799547     209363 
2016       664378     172304 
2017       559569     151331 
2018       357467     100391 
2019       874194     213449 
2020       627331     159743 
2021       846739     201474 
2022       630897     180587 
2023       567364     162254 
2024       632462     182103 
2025       125122      35650