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        22289       9422 
1999        13584       5212 
2000        38754      16026 
2001        39545      15364 
2002        41679      17440 
2003        57991      24128 
2004        46558      17864 
2005        81838      25189 
2006       105488      33849 
2007       192663      59519 
2008       114026      32613 
2009        94158      26529 
2010       121005      33326 
2011       160038      44375 
2012       151257      41906 
2013       223757      63733 
2014       569149     145003 
2015       803078     210446 
2016       664919     172486 
2017       557938     150863 
2018       355349      99807 
2019       870873     212595 
2020       623501     158752 
2021       841878     200157 
2022       627584     179626 
2023       563315     161102 
2024       627648     180737 
2025       169378      48274