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         1675        612 
1994         2339        844 
1995         4433       1530 
1996         3605       1266 
1997         2337        797 
1998        23359       9846 
1999        14651       5622 
2000        40874      16976 
2001        41971      16380 
2002        33238      14833 
2003        62337      25837 
2004        48963      18792 
2005        87709      26919 
2006       113619      36237 
2007       208740      63860 
2008       130076      36947 
2009       105709      29672 
2010       122719      34024 
2011       185440      51253 
2012       171418      47412 
2013       268310      76061 
2014       667398     170184 
2015       779968     206667 
2016       574575     153850 
2017       546935     150771 
2018       408489     114626 
2019       925268     225984 
2020       720507     184988 
2021      1070384     251564 
2022       694043     198547 
2023       643321     185117 
2024         9222       2831