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        22102       9359 
1999        13572       5207 
2000        38725      16010 
2001        39507      15349 
2002        36806      15812 
2003        57876      24082 
2004        46459      17825 
2005        81683      25142 
2006       105328      33800 
2007       192338      59432 
2008       113296      32423 
2009        93796      26429 
2010       124168      34085 
2011       159213      44153 
2012       150483      41695 
2013       222890      63492 
2014       567201     144499 
2015       811360     213062 
2016       663075     172031 
2017       556374     150473 
2018       354127      99473 
2019       868697     212018 
2020       621288     158161 
2021       837989     199146 
2022       624945     178869 
2023       561923     160711 
2024       624529     179876 
2025       188723      53817