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         3105       1083 
1996         2986       1055 
1997         1899        655 
1998        22335       9438 
1999        13608       5223 
2000        38821      16055 
2001        39588      15383 
2002        30998      13887 
2003        58131      24184 
2004        46665      17907 
2005        82044      25247 
2006       105702      33912 
2007       193179      59659 
2008       114858      32830 
2009        94622      26658 
2010       113877      31620 
2011       161013      44642 
2012       155136      43132 
2013       227972      65066 
2014       572325     146067 
2015       801438     209956 
2016       670281     174109 
2017       563022     152436 
2018       362252     101872 
2019       875820     213954 
2020       626565     159559 
2021       845927     201250 
2022       630449     180454 
2023       566910     162117 
2024       632095     181987 
2025       129748      36866