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        14603       5603 
2000        40681      16892 
2001        41720      16274 
2002        32863      14681 
2003        61856      25638 
2004        48588      18644 
2005        86804      26664 
2006       112370      35868 
2007       207272      63459 
2008       128057      36397 
2009       104285      29281 
2010       121056      33583 
2011       182466      50448 
2012       169243      46820 
2013       263576      74744 
2014       655497     167132 
2015       765788     202953 
2016       578723     154373 
2017       601325     160523 
2018       406605     114046 
2019       933032     227655 
2020       710901     182478 
2021       922908     221937 
2022       690101     197321 
2023       622159     179034 
2024       115005      33087