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          444        170 
1992          721        293 
1993         1283        478 
1994         1631        600 
1995         2900       1014 
1996         2895       1024 
1997         1787        619 
1998        21450       9127 
1999        12872       4961 
2000        37990      15690 
2001        39321      15241 
2002        32477      14309 
2003        56243      23444 
2004        45334      17419 
2005        79840      24602 
2006       102820      33069 
2007       187412      58111 
2008       106296      30548 
2009        89180      25187 
2010       141322      38010 
2011       150457      41786 
2012       141472      39253 
2013       214638      61205 
2014       545821     138945 
2015       794789     209160 
2016       644820     167421 
2017       543506     147109 
2018       337891      95003 
2019       849259     207355 
2020       591123     149956 
2021       801959     189697 
2022       607538     173920 
2023       547247     156616 
2024       605413     173933 
2025       515716     147005