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         4427       1528 
1996         3605       1266 
1997         2334        796 
1998        23334       9837 
1999        14623       5612 
2000        40781      16935 
2001        41856      16331 
2002        33042      14752 
2003        62128      25755 
2004        48786      18721 
2005        87229      26785 
2006       113101      36080 
2007       208107      63687 
2008       129213      36711 
2009       104923      29457 
2010       121975      33828 
2011       183889      50832 
2012       170456      47152 
2013       266028      75434 
2014       662527     168941 
2015       774729     205271 
2016       575987     154057 
2017       574522     155647 
2018       407656     114359 
2019       927281     226379 
2020       714724     183482 
2021       927524     223106 
2022       697300     199292 
2023       633379     182244 
2024        53183      15436