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          468        178 
1992          740        300 
1993         1296        483 
1994         1661        610 
1995         3000       1048 
1996         2956       1045 
1997         1822        631 
1998        21596       9189 
1999        13161       5062 
2000        38443      15891 
2001        39274      15255 
2002        32174      14247 
2003        57482      23927 
2004        46126      17706 
2005        80904      24921 
2006       104372      33527 
2007       190916      59053 
2008       111284      31888 
2009        92257      26019 
2010       144452      38821 
2011       156276      43373 
2012       147623      40921 
2013       219329      62517 
2014       563158     143535 
2015       798158     210086 
2016       656343     170572 
2017       552688     149632 
2018       349675      98252 
2019       860929     210177 
2020       613998     156258 
2021       826028     196086 
2022       617580     176791 
2023       556618     159234 
2024       613341     176708 
2025       282305      81122