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         3096       1080 
1996         2983       1054 
1997         1872        646 
1998        22230       9402 
1999        13582       5211 
2000        38758      16026 
2001        39540      15362 
2002        31233      13958 
2003        57982      24125 
2004        46558      17864 
2005        81824      25185 
2006       105471      33844 
2007       192629      59510 
2008       113979      32600 
2009        94154      26528 
2010       120998      33324 
2011       159994      44363 
2012       151220      41896 
2013       223713      63721 
2014       569138     144998 
2015       806392     211358 
2016       664869     172473 
2017       557920     150854 
2018       355250      99781 
2019       871057     212632 
2020       623465     158737 
2021       841717     200125 
2022       627456     179589 
2023       563227     161078 
2024       627451     180686 
2025       169371      48260