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         1869        645 
1998        22132       9369 
1999        13575       5208 
2000        38731      16013 
2001        39520      15353 
2002        31167      13933 
2003        57913      24097 
2004        46492      17838 
2005        81734      25158 
2006       105374      33814 
2007       192430      59457 
2008       113492      32474 
2009        93881      26453 
2010       120785      33266 
2011       159456      44218 
2012       150699      41754 
2013       223276      63597 
2014       568177     144733 
2015       814628     213603 
2016       664132     172279 
2017       557036     150604 
2018       354385      99537 
2019       869745     212281 
2020       622180     158388 
2021       839162     199469 
2022       625801     179116 
2023       562385     160837 
2024       625318     180094 
2025       192679      54874