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         2333        842 
1995         4430       1529 
1996         3605       1266 
1997         2334        796 
1998        23334       9837 
1999        14626       5613 
2000        40779      16934 
2001        41861      16333 
2002        33050      14755 
2003        62147      25762 
2004        48806      18729 
2005        87260      26793 
2006       113116      36085 
2007       208130      63693 
2008       129246      36720 
2009       104943      29463 
2010       122010      33837 
2011       183948      50848 
2012       170487      47160 
2013       266132      75462 
2014       662652     168974 
2015       775046     205351 
2016       575484     153935 
2017       573250     155383 
2018       407492     114319 
2019       927221     226370 
2020       714944     183541 
2021       927596     223145 
2022       697440     199331 
2023       633658     182323 
2024        48387      14027