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         3599       1264 
1997         2340        798 
1998        23328       9834 
1999        14603       5603 
2000        40681      16892 
2001        41716      16272 
2002        32855      14678 
2003        61847      25634 
2004        48573      18638 
2005        86793      26661 
2006       112353      35863 
2007       207209      63442 
2008       128022      36388 
2009       104270      29277 
2010       120996      33567 
2011       182363      50420 
2012       169172      46801 
2013       263435      74705 
2014       655360     167096 
2015       765371     202850 
2016       578952     154424 
2017       601448     160671 
2018       406452     114003 
2019       933273     227698 
2020       710636     182405 
2021       922371     221811 
2022       689894     197263 
2023       621976     178983 
2024       115474      33213