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          743        301 
1993         1308        487 
1994         1681        617 
1995         3057       1067 
1996         2980       1053 
1997         1863        643 
1998        21703       9225 
1999        13541       5194 
2000        38637      15973 
2001        39462      15329 
2002        32275      14297 
2003        57781      24042 
2004        46364      17788 
2005        81472      25079 
2006       105168      33753 
2007       191948      59325 
2008       112524      32217 
2009        93290      26292 
2010       141349      38157 
2011       158373      43926 
2012       149614      41452 
2013       221591      63127 
2014       564964     143934 
2015       798261     210071 
2016       659718     171443 
2017       555152     150280 
2018       352210      98945 
2019       864638     211041 
2020       617956     157276 
2021       832133     197612 
2022       621411     177869 
2023       559296     159972 
2024       617837     178002 
2025       207615      59287