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          532        200 
1992          936        367 
1993         1669        610 
1994         2339        844 
1995         4430       1529 
1996         3605       1266 
1997         2334        796 
1998        23337       9838 
1999        14628       5614 
2000        40797      16942 
2001        41875      16339 
2002        33075      14765 
2003        62156      25765 
2004        48821      18735 
2005        87324      26809 
2006       113173      36103 
2007       208185      63708 
2008       129321      36740 
2009       104995      29478 
2010       122087      33858 
2011       184066      50880 
2012       170610      47195 
2013       266295      75507 
2014       662926     169046 
2015       775346     205432 
2016       575205     153885 
2017       568741     154693 
2018       407483     114327 
2019       926543     226164 
2020       715217     183619 
2021       927867     223196 
2022       690236     197452 
2023       633867     182392 
2024        48454      14047