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         3093       1079 
1996         2980       1053 
1997         1866        644 
1998        22102       9359 
1999        13572       5207 
2000        38725      16010 
2001        39507      15349 
2002        36813      15814 
2003        57879      24083 
2004        46459      17825 
2005        81694      25145 
2006       105328      33800 
2007       192338      59432 
2008       113296      32423 
2009        93799      26430 
2010       124171      34086 
2011       159220      44155 
2012       150491      41697 
2013       222898      63494 
2014       567365     144532 
2015       816636     214276 
2016       663278     172070 
2017       556393     150478 
2018       354096      99463 
2019       868655     212005 
2020       621315     158165 
2021       838036     199160 
2022       624966     178875 
2023       561930     160713 
2024       624552     179883 
2025       188713      53816