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        40715      16908 
2001        41769      16293 
2002        32921      14704 
2003        61910      25661 
2004        48622      18658 
2005        86915      26697 
2006       112600      35936 
2007       207565      63539 
2008       128443      36503 
2009       104459      29331 
2010       121382      33670 
2011       182932      50572 
2012       169647      46928 
2013       264505      75006 
2014       659372     168017 
2015       771817     204347 
2016       577985     154130 
2017       592705     158465 
2018       406774     114102 
2019       930618     227216 
2020       712286     182845 
2021       924323     222299 
2022       691359     197670 
2023       624979     179848 
2024       102469      29663