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        22072       9349 
1999        13572       5207 
2000        38712      16004 
2001        39500      15346 
2002        49340      19990 
2003        57861      24076 
2004        46449      17821 
2005        81665      25137 
2006       105311      33795 
2007       192276      59415 
2008       113184      32393 
2009        93733      26411 
2010       129412      35338 
2011       159107      44124 
2012       150408      41675 
2013       222759      63456 
2014       566862     144419 
2015       797890     209857 
2016       658274     170928 
2017       554843     150179 
2018       353792      99392 
2019       867579     211786 
2020       620754     158013 
2021       837406     198981 
2022       624510     178748 
2023       561520     160602 
2024       623489     179587 
2025       189831      54204