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          669        275 
1993         1213        455 
1994         1552        577 
1995         2585        909 
1996         2785        986 
1997         2684        915 
1998        24221       8649 
1999        13043       4970 
2000        36771      15113 
2001        41851      16442 
2002        35408      15151 
2003        57758      23638 
2004        45473      17310 
2005       305520     137513 
2006       332793     148465 
2007       193650      59911 
2008       110285      31415 
2009        90962      25414 
2010       139074      37022 
2011       146839      39932 
2012       174581      38076 
2013       230509      58108 
2014       498811     123469 
2015       739082     192896 
2016       619740     160017 
2017       519008     141171 
2018       308709      87281 
2019       814038     199522 
2020       536557     136180 
2021       726304     170369 
2022       564447     161821 
2023       516844     148027 
2024       558163     160396 
2025       534937     151599 
2026       269849      59344