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          735        298 
1993         1283        478 
1994         1655        608 
1995         2948       1030 
1996         2944       1041 
1997         1813        628 
1998        21556       9172 
1999        13067       5029 
2000        38241      15802 
2001        39147      15201 
2002        30593      13707 
2003        57163      23803 
2004        45849      17603 
2005        80554      24816 
2006       103876      33380 
2007       190007      58808 
2008       109962      31534 
2009        91471      25803 
2010       143275      38520 
2011       154426      42866 
2012       145780      40424 
2013       217651      62050 
2014       558379     142283 
2015       797806     209845 
2016       654712     170092 
2017       549609     148769 
2018       345696      97155 
2019       858138     209389 
2020       607351     154449 
2021       817314     193866 
2022       613703     175685 
2023       553465     158359 
2024       608192     175116 
2025       363508     104561