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        22093       9356 
1999        13572       5207 
2000        38719      16007 
2001        39507      15349 
2002        31217      13949 
2003        57873      24081 
2004        46457      17824 
2005        81676      25140 
2006       105325      33799 
2007       192318      59426 
2008       113261      32414 
2009        93784      26426 
2010       129450      35348 
2011       159176      44143 
2012       150470      41691 
2013       222838      63477 
2014       567043     144468 
2015       797944     209831 
2016       659270     171186 
2017       555196     150277 
2018       353962      99431 
2019       868114     211878 
2020       621018     158085 
2021       837702     199066 
2022       624723     178807 
2023       561762     160666 
2024       623795     179675 
2025       188059      53697