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        14605       5604 
2000        40695      16899 
2001        41747      16284 
2002        32893      14692 
2003        61863      25641 
2004        48603      18650 
2005        86832      26673 
2006       112450      35891 
2007       207401      63495 
2008       128166      36428 
2009       104330      29294 
2010       121176      33615 
2011       182699      50510 
2012       169400      46863 
2013       263909      74839 
2014       657152     167523 
2015       771080     204148 
2016       578490     154273 
2017       598351     159797 
2018       406694     114077 
2019       931759     227454 
2020       711418     182619 
2021       923267     222031 
2022       690519     197439 
2023       624250     179627 
2024       106641      30756