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         4430       1529 
1996         3605       1266 
1997         2334        796 
1998        23334       9837 
1999        14626       5613 
2000        40779      16934 
2001        41861      16333 
2002        33052      14756 
2003        62147      25762 
2004        48809      18730 
2005        87270      26796 
2006       113124      36088 
2007       208141      63696 
2008       129254      36722 
2009       104947      29464 
2010       122013      33838 
2011       183988      50859 
2012       170494      47162 
2013       266158      75469 
2014       662756     168998 
2015       775099     205366 
2016       575270     153906 
2017       571695     155112 
2018       407434     114303 
2019       927182     226337 
2020       714989     183554 
2021       927587     223141 
2022       697514     199352 
2023       633684     182335 
2024        48426      14039