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         3078       1074 
1996         2980       1053 
1997         1866        644 
1998        21858       9277 
1999        13570       5202 
2000        38672      15987 
2001        39478      15336 
2002        35022      15214 
2003        57819      24058 
2004        46394      17800 
2005        81556      25105 
2006       105226      33770 
2007       192088      59364 
2008       112767      32281 
2009        93510      26351 
2010       135145      36708 
2011       158668      44004 
2012       149876      41525 
2013       221996      63244 
2014       565604     144092 
2015       798570     210117 
2016       659943     171488 
2017       555296     150347 
2018       352924      99144 
2019       866234     211464 
2020       619237     157632 
2021       834272     198130 
2022       622794     178263 
2023       560320     160265 
2024       620683     178809 
2025       206054      58884