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         3111       1085 
1996         3005       1062 
1997         1934        667 
1998        22346       9443 
1999        13620       5227 
2000        38920      16100 
2001        39678      15424 
2002        31113      13940 
2003        58336      24266 
2004        46864      17985 
2005        82344      25337 
2006       106041      34011 
2007       193960      59871 
2008       115778      33075 
2009        95392      26871 
2010       110013      30691 
2011       162309      44994 
2012       153661      42566 
2013       226318      64448 
2014       569217     145093 
2015       790179     207024 
2016       664566     172404 
2017       561897     151990 
2018       360108     101123 
2019       877556     214314 
2020       630913     160730 
2021       851118     202609 
2022       633655     181384 
2023       572946     163697 
2024       636593     183331 
2025        80346      22633