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         2333        842 
1995         4427       1528 
1996         3602       1265 
1997         2334        796 
1998        23334       9837 
1999        14621       5611 
2000        40756      16925 
2001        41829      16319 
2002        33003      14735 
2003        62057      25721 
2004        48724      18695 
2005        87156      26764 
2006       112958      36038 
2007       207900      63630 
2008       128946      36639 
2009       104724      29403 
2010       121764      33774 
2011       183551      50742 
2012       170162      47071 
2013       265478      75279 
2014       661621     168708 
2015       774037     205082 
2016       577027     154240 
2017       582388     156961 
2018       407050     114189 
2019       925339     225955 
2020       713897     183258 
2021       972577     232577 
2022       696147     198963 
2023       632721     182046 
2024        64312      18587