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         2329        840 
1995         4425       1527 
1996         3602       1265 
1997         2340        798 
1998        23328       9834 
1999        14605       5604 
2000        40685      16894 
2001        41728      16277 
2002        32871      14684 
2003        61861      25640 
2004        48600      18649 
2005        86813      26667 
2006       112399      35877 
2007       207367      63485 
2008       128110      36413 
2009       104305      29287 
2010       121104      33596 
2011       182592      50482 
2012       169319      46841 
2013       263796      74806 
2014       655772     167205 
2015       767858     203425 
2016       578269     154254 
2017       599955     160195 
2018       406789     114095 
2019       932785     227638 
2020       711183     182556 
2021       949996     227189 
2022       690362     197395 
2023       622813     179221 
2024       114935      33070