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        40687      16895 
2001        41728      16277 
2002        32871      14684 
2003        61861      25640 
2004        48600      18649 
2005        86813      26667 
2006       112407      35879 
2007       207378      63488 
2008       128121      36416 
2009       104309      29288 
2010       121131      33603 
2011       182619      50489 
2012       169346      46848 
2013       263828      74815 
2014       655830     167221 
2015       769593     203797 
2016       578138     154219 
2017       598869     159993 
2018       406748     114085 
2019       932157     227547 
2020       711213     182565 
2021       950072     227210 
2022       690388     197402 
2023       623088     179302 
2024       114228      32884