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          749        303 
1993         1316        490 
1994         1692        621 
1995         3120       1088 
1996         3008       1063 
1997         1961        676 
1998        22385       9458 
1999        13661       5242 
2000        39025      16149 
2001        39779      15468 
2002        31209      13983 
2003        58496      24332 
2004        46928      18010 
2005        82550      25400 
2006       106278      34081 
2007       194392      59988 
2008       116279      33211 
2009        95812      26985 
2010       110535      30830 
2011       163066      45197 
2012       154285      42738 
2013       227236      64702 
2014       561046     143319 
2015       775813     203544 
2016       664802     172468 
2017       564291     152556 
2018       361803     101588 
2019       880193     214957 
2020       633219     161362 
2021       853710     203293 
2022       635305     181861 
2023       571442     163615 
2024       640898     184573 
2025        51161      14688