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       103883      33382 
2007       190011      58809 
2008       109984      31539 
2009        91471      25803 
2010       143278      38521 
2011       154434      42868 
2012       145806      40431 
2013       217659      62052 
2014       558398     142289 
2015       797843     209855 
2016       654744     170100 
2017       549641     148778 
2018       345733      97165 
2019       858182     209401 
2020       607391     154460 
2021       817366     193881 
2022       613723     175691 
2023       553465     158359 
2024       608237     175130 
2025       363621     104585