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         2573        906 
1996         2773        982 
1997         2672        911 
1998        24205       8642 
1999        13026       4963 
2000        36730      15094 
2001        41808      16423 
2002        35362      15133 
2003        57685      23608 
2004        45421      17289 
2005       305326     137432 
2006       332581     148378 
2007       193514      59875 
2008       110110      31370 
2009        90756      25359 
2010       138910      36980 
2011       146528      39850 
2012       174346      38011 
2013       230264      58045 
2014       484396     120197 
2015       738470     192722 
2016       619149     159860 
2017       518356     141000 
2018       308235      87148 
2019       813453     199358 
2020       536036     136046 
2021       725554     170204 
2022       563880     161662 
2023       516320     147885 
2024       557573     160235 
2025       534015     151355 
2026       272583      60054