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         3602       1265 
1997         2340        798 
1998        23334       9837 
1999        14618       5609 
2000        40751      16923 
2001        41820      16315 
2002        32992      14730 
2003        62033      25711 
2004        48710      18690 
2005        87078      26744 
2006       112808      35994 
2007       207799      63603 
2008       128769      36591 
2009       104665      29386 
2010       121662      33746 
2011       183345      50686 
2012       169909      47001 
2013       265118      75178 
2014       661129     168576 
2015       773365     204899 
2016       577389     154213 
2017       586816     157609 
2018       406802     114120 
2019       926513     226219 
2020       713004     183014 
2021      1075972     253321 
2022       692988     198119 
2023       630237     181342 
2024        81315      23670