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          468        178 
1992          743        301 
1993         1308        487 
1994         1678        616 
1995         3051       1065 
1996         2980       1053 
1997         1860        642 
1998        21677       9216 
1999        13484       5174 
2000        38617      15965 
2001        39438      15318 
2002        32585      14400 
2003        57753      24029 
2004        46316      17770 
2005        81404      25059 
2006       105079      33725 
2007       191847      59297 
2008       112319      32162 
2009        93135      26251 
2010       143993      38739 
2011       157988      43823 
2012       149327      41374 
2013       221122      62996 
2014       565242     144006 
2015       798420     210130 
2016       659216     171312 
2017       554846     150180 
2018       351656      98787 
2019       863907     210870 
2020       617185     157066 
2021       830346     197168 
2022       620009     177462 
2023       558614     159776 
2024       617534     177915 
2025       216942      62038