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        22123       9366 
1999        13575       5208 
2000        38731      16013 
2001        39520      15353 
2002        31095      13909 
2003        57913      24097 
2004        46492      17838 
2005        81726      25155 
2006       105374      33814 
2007       192412      59452 
2008       113463      32466 
2009        93867      26449 
2010       124281      34114 
2011       159416      44208 
2012       150668      41746 
2013       223238      63586 
2014       568059     144700 
2015       815265     213782 
2016       664056     172257 
2017       556979     150588 
2018       354320      99518 
2019       869626     212255 
2020       622054     158352 
2021       838943     199414 
2022       625686     179082 
2023       562322     160818 
2024       625219     180066 
2025       192063      54732