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        39027      16150 
2001        39794      15474 
2002        31218      13987 
2003        58503      24335 
2004        46933      18012 
2005        82569      25406 
2006       106308      34089 
2007       194424      59997 
2008       116337      33227 
2009        95865      26999 
2010       110563      30837 
2011       163130      45214 
2012       154343      42754 
2013       227350      64733 
2014       560131     143136 
2015       774410     203184 
2016       664821     172471 
2017       564475     152599 
2018       361923     101621 
2019       880467     215027 
2020       633402     161410 
2021       854061     203360 
2022       635501     181917 
2023       571617     163665 
2024       641561     184763 
2025        51465      14778