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          465        177 
1992          732        297 
1993         1283        478 
1994         1643        604 
1995         2933       1025 
1996         2936       1038 
1997         1801        624 
1998        21533       9162 
1999        13003       5006 
2000        38178      15777 
2001        39070      15171 
2002        30904      13807 
2003        57011      23743 
2004        45756      17572 
2005        80434      24780 
2006       103686      33324 
2007       189599      58696 
2008       109238      31338 
2009        91114      25704 
2010       142855      38409 
2011       153631      42647 
2012       145142      40250 
2013       217060      61891 
2014       556111     141664 
2015       795881     209333 
2016       652689     169540 
2017       548219     148388 
2018       344113      96724 
2019       856140     208896 
2020       604223     153570 
2021       814056     193025 
2022       612563     175363 
2023       552462     158094 
2024       606867     174704 
2025       414694     119587