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        22316       9431 
1999        13584       5212 
2000        38754      16026 
2001        39547      15365 
2002        31177      13940 
2003        58005      24131 
2004        46582      17873 
2005        81853      25193 
2006       105508      33855 
2007       192673      59522 
2008       114064      32622 
2009        94199      26540 
2010       119540      32969 
2011       160157      44406 
2012       151317      41923 
2013       223817      63750 
2014       569020     144960 
2015       802314     210158 
2016       665564     172647 
2017       558136     150913 
2018       355489      99844 
2019       871274     212693 
2020       623846     158806 
2021       842181     200245 
2022       627921     179723 
2023       563457     161143 
2024       628284     180903 
2025       169888      48398