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         3093       1079 
1996         2980       1053 
1997         1866        644 
1998        22117       9364 
1999        13572       5207 
2000        38729      16012 
2001        39509      15350 
2002        31038      13889 
2003        57885      24085 
2004        46466      17828 
2005        81701      25147 
2006       105349      33806 
2007       192374      59442 
2008       113342      32435 
2009        93829      26438 
2010       124203      34094 
2011       159274      44170 
2012       150535      41709 
2013       223042      63531 
2014       567703     144609 
2015       814559     213644 
2016       663734     172166 
2017       556755     150525 
2018       354140      99470 
2019       869210     212142 
2020       621710     158258 
2021       838333     199241 
2022       625290     178968 
2023       562155     160770 
2024       624852     179966 
2025       190013      54168