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        22102       9359 
1999        13572       5207 
2000        38721      16008 
2001        39507      15349 
2002        36803      15811 
2003        57873      24081 
2004        46457      17824 
2005        81680      25141 
2006       105328      33800 
2007       192335      59431 
2008       113285      32420 
2009        93796      26429 
2010       124168      34085 
2011       159199      44149 
2012       150473      41692 
2013       222877      63488 
2014       567081     144476 
2015       805495     211559 
2016       660538     171487 
2017       556363     150470 
2018       354106      99467 
2019       868610     211993 
2020       621309     158167 
2021       837949     199135 
2022       624898     178855 
2023       561907     160707 
2024       624427     179847 
2025       188667      53805