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          746        302 
1993         1308        487 
1994         1684        618 
1995         3096       1080 
1996         2983       1054 
1997         1872        646 
1998        22310       9429 
1999        13584       5212 
2000        38754      16026 
2001        39547      15365 
2002        42083      17575 
2003        57993      24129 
2004        46574      17870 
2005        81841      25190 
2006       105503      33853 
2007       192673      59522 
2008       114054      32619 
2009        94185      26536 
2010       119524      32965 
2011       160097      44390 
2012       151296      41916 
2013       223793      63743 
2014       569072     144979 
2015       802828     210316 
2016       665451     172619 
2017       558093     150901 
2018       355427      99829 
2019       871212     212675 
2020       623767     158786 
2021       842133     200231 
2022       627789     179685 
2023       563413     161131 
2024       628212     180884 
2025       169739      48360