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        38823      16056 
2001        39593      15385 
2002        31010      13892 
2003        58139      24188 
2004        46677      17912 
2005        82053      25250 
2006       105709      33914 
2007       193223      59671 
2008       114908      32843 
2009        94695      26678 
2010       113916      31630 
2011       161080      44660 
2012       155185      43145 
2013       228020      65079 
2014       572203     146042 
2015       801090     209862 
2016       669750     173962 
2017       563141     152464 
2018       362394     101911 
2019       875960     213995 
2020       626674     159589 
2021       846225     201325 
2022       630593     180498 
2023       566993     162153 
2024       632118     182004 
2025       125527      35727