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         3602       1265 
1997         2340        798 
1998        23334       9837 
1999        14622       5611 
2000        40751      16923 
2001        41820      16315 
2002        32992      14730 
2003        62036      25712 
2004        48713      18691 
2005        87089      26747 
2006       112830      36000 
2007       207814      63607 
2008       128790      36597 
2009       104681      29390 
2010       121674      33749 
2011       183364      50691 
2012       169939      47009 
2013       265153      75187 
2014       661166     168587 
2015       773425     204916 
2016       577067     154198 
2017       586370     157547 
2018       406792     114118 
2019       925750     226071 
2020       713051     183030 
2021       955677     228821 
2022       693026     198130 
2023       630552     181432 
2024        77154      22398