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         1310        488 
1994         1692        621 
1995         3114       1086 
1996         3008       1063 
1997         1961        676 
1998        22346       9443 
1999        13622       5228 
2000        38933      16106 
2001        39700      15433 
2002        31151      13956 
2003        58376      24282 
2004        46884      17993 
2005        82418      25359 
2006       106126      34036 
2007       194134      59918 
2008       115942      33120 
2009        95535      26911 
2010       110191      30739 
2011       162617      45076 
2012       153941      42644 
2013       226672      64544 
2014       564094     143992 
2015       785377     205745 
2016       664326     172361 
2017       562469     152145 
2018       360757     101305 
2019       878682     214571 
2020       631979     161018 
2021       852313     202928 
2022       634394     181597 
2023       573503     163983 
2024       640324     184388 
2025        65377      18641