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         3105       1083 
1996         2986       1055 
1997         1896        654 
1998        22333       9437 
1999        13608       5223 
2000        38813      16052 
2001        39588      15383 
2002        30993      13885 
2003        58125      24181 
2004        46655      17903 
2005        82039      25245 
2006       105694      33910 
2007       193150      59651 
2008       114792      32812 
2009        94601      26652 
2010       113850      31613 
2011       160971      44631 
2012       155071      43115 
2013       227919      65052 
2014       572161     146025 
2015       801438     209957 
2016       670386     174142 
2017       562885     152400 
2018       362096     101830 
2019       875514     213875 
2020       626350     159499 
2021       845597     201171 
2022       630224     180388 
2023       566637     162040 
2024       631931     181941 
2025       134414      37999