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          471        179 
1992          746        302 
1993         1308        487 
1994         1684        618 
1995         3087       1077 
1996         2980       1053 
1997         1866        644 
1998        22045       9340 
1999        13570       5206 
2000        38701      16000 
2001        39490      15341 
2002        49328      19985 
2003        57850      24072 
2004        46442      17818 
2005        81629      25126 
2006       105286      33787 
2007       192230      59403 
2008       113109      32372 
2009        93677      26396 
2010       129792      35430 
2011       159001      44095 
2012       150287      41640 
2013       222532      63394 
2014       566530     144336 
2015       797841     209867 
2016       658113     170889 
2017       554618     150115 
2018       353643      99355 
2019       867296     211719 
2020       620216     157897 
2021       836930     198843 
2022       624119     178639 
2023       561207     160518 
2024       622747     179382 
2025       196617      56072