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        22262       9413 
1999        13584       5212 
2000        38763      16028 
2001        39545      15364 
2002        33042      14561 
2003        57991      24128 
2004        46558      17864 
2005        81834      25188 
2006       105482      33847 
2007       192644      59514 
2008       113998      32605 
2009        94158      26529 
2010       121005      33326 
2011       160011      44368 
2012       151224      41897 
2013       223719      63723 
2014       569119     144996 
2015       804434     210819 
2016       664886     172477 
2017       557953     150863 
2018       355306      99796 
2019       870997     212628 
2020       623474     158742 
2021       841806     200136 
2022       627546     179615 
2023       563278     161093 
2024       627515     180701 
2025       169260      48241