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        32972      14474 
2003        56243      23444 
2004        45334      17419 
2005        79840      24602 
2006       102824      33070 
2007       187419      58113 
2008       106307      30551 
2009        89192      25190 
2010       141336      38014 
2011       150479      41792 
2012       141482      39256 
2013       214647      61207 
2014       545870     138958 
2015       794711     209142 
2016       644862     167432 
2017       543561     147124 
2018       337922      95012 
2019       849257     207354 
2020       591182     149973 
2021       802027     189717 
2022       607622     173943 
2023       547277     156625 
2024       606814     174144 
2025       528813     150854