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        33009      14737 
2003        62057      25721 
2004        48726      18696 
2005        87164      26766 
2006       112964      36040 
2007       207917      63634 
2008       128960      36643 
2009       104732      29405 
2010       121774      33775 
2011       183569      50747 
2012       170187      47077 
2013       265528      75292 
2014       661673     168722 
2015       774077     205094 
2016       576751     154190 
2017       580493     156577 
2018       407063     114191 
2019       925312     225947 
2020       713952     183269 
2021       928359     223292 
2022       696311     199008 
2023       632722     182047 
2024        63307      18346