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         3087       1077 
1996         2980       1053 
1997         1866        644 
1998        22069       9348 
1999        13572       5207 
2000        38712      16004 
2001        39498      15345 
2002        49337      19989 
2003        57858      24075 
2004        46447      17820 
2005        81651      25133 
2006       105300      33791 
2007       192265      59412 
2008       113175      32390 
2009        93713      26406 
2010       129394      35332 
2011       159077      44116 
2012       150365      41663 
2013       222725      63446 
2014       566735     144387 
2015       797785     209842 
2016       658186     170906 
2017       554778     150160 
2018       353781      99389 
2019       867541     211774 
2020       620662     157987 
2021       837270     198942 
2022       624433     178725 
2023       561477     160590 
2024       623239     179518 
2025       190174      54298