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        14613       5607 
2000        40701      16902 
2001        41754      16287 
2002        32909      14698 
2003        61880      25648 
2004        48605      18651 
2005        86874      26686 
2006       112525      35913 
2007       207518      63526 
2008       128312      36467 
2009       104396      29314 
2010       121289      33645 
2011       182834      50546 
2012       169518      46894 
2013       264216      74926 
2014       657529     167622 
2015       771454     204251 
2016       578419     154245 
2017       595876     159186 
2018       406910     114134 
2019       930957     227292 
2020       711872     182731 
2021       923847     222179 
2022       690929     197551 
2023       625094     179851 
2024       102229      29592