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          532        200 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4425       1527 
1996         3602       1265 
1997         2340        798 
1998        23328       9834 
1999        14613       5607 
2000        40701      16902 
2001        41754      16287 
2002        32907      14697 
2003        61880      25648 
2004        48603      18650 
2005        86859      26681 
2006       112491      35903 
2007       207456      63510 
2008       128214      36441 
2009       104364      29305 
2010       121234      33631 
2011       182758      50526 
2012       169447      46875 
2013       264060      74881 
2014       657375     167581 
2015       771309     204210 
2016       578420     154240 
2017       596506     159330 
2018       406666     114072 
2019       930889     227265 
2020       711701     182682 
2021       923662     222121 
2022       690693     197485 
2023       624962     179811 
2024       102756      29706