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        23325       9833 
1999        14603       5603 
2000        40679      16891 
2001        41716      16272 
2002        32852      14677 
2003        61844      25633 
2004        48570      18637 
2005        86782      26658 
2006       112325      35856 
2007       207133      63421 
2008       128000      36382 
2009       104240      29269 
2010       120977      33563 
2011       182300      50403 
2012       169127      46789 
2013       263339      74677 
2014       655239     167063 
2015       765097     202783 
2016       579060     154437 
2017       602330     160845 
2018       406504     114013 
2019       933144     227640 
2020       710412     182339 
2021       922166     221750 
2022       689767     197227 
2023       621863     178951 
2024       116263      33409