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         1925        664 
1998        22341       9441 
1999        13620       5227 
2000        38914      16098 
2001        39673      15421 
2002        31110      13939 
2003        58312      24255 
2004        46835      17974 
2005        82309      25326 
2006       106024      34006 
2007       193896      59853 
2008       115674      33047 
2009        95306      26846 
2010       109926      30668 
2011       162190      44962 
2012       153497      42520 
2013       226173      64409 
2014       569028     145064 
2015       791103     207219 
2016       664817     172461 
2017       561568     151895 
2018       359772     101031 
2019       877204     214216 
2020       630409     160588 
2021       850351     202431 
2022       633331     181290 
2023       572334     163521 
2024       636236     183230 
2025       100187      28402