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        13578       5209 
2000        38731      16013 
2001        39520      15353 
2002        31179      13937 
2003        57916      24098 
2004        46495      17839 
2005        81734      25158 
2006       105376      33815 
2007       192437      59459 
2008       113513      32480 
2009        93881      26453 
2010       120788      33267 
2011       159472      44222 
2012       150725      41762 
2013       223314      63608 
2014       568279     144761 
2015       813519     213295 
2016       664175     172290 
2017       557112     150626 
2018       354439      99552 
2019       869818     212300 
2020       622222     158399 
2021       839368     199520 
2022       625941     179155 
2023       562418     160847 
2024       625532     180155 
2025       192389      54764