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         2339        844 
1995         4430       1529 
1996         3605       1266 
1997         2334        796 
1998        23340       9839 
1999        14634       5616 
2000        40801      16944 
2001        41888      16345 
2002        33096      14773 
2003        62177      25773 
2004        48839      18742 
2005        87341      26814 
2006       113228      36121 
2007       208209      63715 
2008       129373      36755 
2009       105042      29491 
2010       122134      33871 
2011       184147      50901 
2012       170688      47215 
2013       266380      75532 
2014       663224     169121 
2015       775671     205513 
2016       574731     153810 
2017       565690     154310 
2018       407333     114280 
2019       925310     225931 
2020       715229     183648 
2021       928048     223217 
2022       690512     197530 
2023       634803     182655 
2024        48534      14070