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        14623       5612 
2000        40779      16934 
2001        41856      16331 
2002        33047      14754 
2003        62136      25758 
2004        48806      18729 
2005        87252      26791 
2006       113116      36085 
2007       208122      63691 
2008       129246      36720 
2009       104943      29463 
2010       122006      33836 
2011       183938      50845 
2012       170483      47159 
2013       266120      75460 
2014       662615     168965 
2015       774985     205335 
2016       575713     153992 
2017       574382     155633 
2018       407534     114332 
2019       927312     226392 
2020       714934     183538 
2021       927442     223105 
2022       697411     199323 
2023       633575     182299 
2024        49249      14260