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        24209       8644 
1999        13034       4966 
2000        36730      15094 
2001        41808      16423 
2002        35367      15134 
2003        57690      23610 
2004        45424      17290 
2005       305356     137441 
2006       332602     148384 
2007       193526      59878 
2008       110135      31377 
2009        90796      25370 
2010       138935      36987 
2011       146550      39856 
2012       174380      38020 
2013       230299      58053 
2014       493224     122173 
2015       738525     192739 
2016       619268     159893 
2017       518514     141041 
2018       308341      87178 
2019       813523     199378 
2020       536128     136070 
2021       725614     170220 
2022       563935     161677 
2023       516355     147894 
2024       557596     160241 
2025       533925     151318 
2026       272584      60037