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        38727      16011 
2001        39507      15349 
2002        36813      15814 
2003        57879      24083 
2004        46464      17827 
2005        81697      25146 
2006       105339      33803 
2007       192356      59437 
2008       113322      32430 
2009        93803      26431 
2010       124187      34090 
2011       159245      44162 
2012       150509      41702 
2013       222989      63516 
2014       567618     144590 
2015       816826     214278 
2016       663632     172147 
2017       556781     150533 
2018       354040      99443 
2019       869212     212160 
2020       621520     158225 
2021       838209     199205 
2022       625192     178939 
2023       562120     160760 
2024       624646     179907 
2025       189005      53897