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         2980       1053 
1997         1869        645 
1998        22164       9380 
1999        13580       5210 
2000        38750      16022 
2001        39532      15358 
2002        31213      13950 
2003        57958      24115 
2004        46542      17858 
2005        81776      25170 
2006       105423      33829 
2007       192527      59483 
2008       113763      32545 
2009        94054      26500 
2010       120893      33296 
2011       159798      44309 
2012       151054      41850 
2013       223575      63682 
2014       568795     144906 
2015       808081     211834 
2016       664476     172368 
2017       557671     150783 
2018       354927      99690 
2019       870563     212505 
2020       622987     158614 
2021       840980     199929 
2022       626871     179423 
2023       562911     160989 
2024       627198     180616 
2025       177789      50554