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        13658       5241 
2000        39021      16147 
2001        39777      15467 
2002        31204      13981 
2003        58492      24330 
2004        46928      18010 
2005        82550      25400 
2006       106271      34079 
2007       194384      59986 
2008       116269      33208 
2009        95808      26984 
2010       110530      30829 
2011       163038      45190 
2012       154281      42737 
2013       227222      64698 
2014       561720     143455 
2015       777113     203861 
2016       664871     172486 
2017       564249     152544 
2018       361764     101577 
2019       880150     214945 
2020       633189     161354 
2021       853639     203272 
2022       635274     181852 
2023       571389     163600 
2024       640759     184537 
2025        51130      14676