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         1308        487 
1994         1686        619 
1995         3108       1084 
1996         2986       1055 
1997         1899        655 
1998        22335       9438 
1999        13611       5224 
2000        38829      16058 
2001        39593      15385 
2002        31012      13893 
2003        58139      24188 
2004        46677      17912 
2005        82057      25251 
2006       105709      33914 
2007       193223      59671 
2008       114912      32844 
2009        94706      26681 
2010       113928      31633 
2011       161096      44665 
2012       155206      43151 
2013       228041      65085 
2014       572209     146041 
2015       800731     209765 
2016       669430     173878 
2017       563163     152471 
2018       362418     101918 
2019       875979     214001 
2020       626725     159604 
2021       846270     201339 
2022       630641     180512 
2023       567042     162167 
2024       632125     182006 
2025       124713      35537