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         1316        490 
1994         1692        621 
1995         3120       1088 
1996         3008       1063 
1997         1961        676 
1998        22383       9457 
1999        13658       5241 
2000        39019      16146 
2001        39775      15466 
2002        31202      13980 
2003        58490      24329 
2004        46924      18008 
2005        82526      25393 
2006       106248      34072 
2007       194359      59979 
2008       116233      33199 
2009        95765      26972 
2010       110499      30820 
2011       162957      45169 
2012       154219      42720 
2013       227155      64678 
2014       561897     143475 
2015       777583     203929 
2016       664457     172386 
2017       564025     152491 
2018       361648     101550 
2019       879996     214902 
2020       633078     161322 
2021       853402     203224 
2022       635194     181828 
2023       571207     163547 
2024       640550     184478 
2025        53913      15400