Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           14          7 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          216         77 
1991          856        306 
1992          664        273 
1993         1213        455 
1994         1552        577 
1995         2576        907 
1996         2779        984 
1997         2684        915 
1998        24211       8645 
1999        13034       4966 
2000        36732      15095 
2001        41813      16425 
2002        35375      15138 
2003        57692      23611 
2004        45424      17290 
2005       305382     137452 
2006       332622     148390 
2007       193533      59880 
2008       110150      31381 
2009        90808      25373 
2010       138943      36989 
2011       146597      39868 
2012       174384      38021 
2013       230326      58060 
2014       498544     123399 
2015       738613     192765 
2016       619299     159902 
2017       518551     141051 
2018       308388      87190 
2019       813573     199393 
2020       536156     136078 
2021       725637     170225 
2022       563960     161684 
2023       516406     147909 
2024       557629     160251 
2025       533999     151341 
2026       272519      60030