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         1678        613 
1994         2339        844 
1995         4436       1531 
1996         3605       1266 
1997         2337        797 
1998        23359       9846 
1999        14654       5623 
2000        40878      16978 
2001        41980      16384 
2002        33259      14842 
2003        62368      25849 
2004        48994      18804 
2005        87779      26941 
2006       113682      36256 
2007       208865      63894 
2008       130204      36982 
2009       105824      29703 
2010       122858      34060 
2011       185728      51329 
2012       171686      47485 
2013       268760      76186 
2014       667968     170342 
2015       780852     206913 
2016       574562     153925 
2017       544417     150505 
2018       411124     115354 
2019       925924     226198 
2020       722392     185484 
2021       932049     224289 
2022       695567     198974 
2023       645407     185700 
2024         4428       1310