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        22295       9424 
1999        13584       5212 
2000        38754      16026 
2001        39547      15365 
2002        42789      17810 
2003        57993      24129 
2004        46561      17865 
2005        81841      25190 
2006       105496      33851 
2007       192667      59520 
2008       114036      32614 
2009        94161      26530 
2010       121009      33327 
2011       160046      44377 
2012       151261      41907 
2013       223765      63735 
2014       569096     144988 
2015       802552     210300 
2016       664896     172483 
2017       557957     150868 
2018       355367      99812 
2019       870845     212587 
2020       623512     158754 
2021       841904     200164 
2022       627610     179634 
2023       563335     161108 
2024       627655     180739 
2025       169392      48278