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        40876      16977 
2001        41980      16384 
2002        33250      14838 
2003        62368      25849 
2004        48981      18799 
2005        87766      26937 
2006       113672      36253 
2007       208834      63886 
2008       130168      36972 
2009       105801      29697 
2010       122830      34053 
2011       185653      51309 
2012       171653      47476 
2013       268651      76155 
2014       667893     170320 
2015       780743     206882 
2016       575044     154026 
2017       548051     151207 
2018       411193     115372 
2019       926563     226342 
2020       722072     185395 
2021       930984     224053 
2022       695387     198923 
2023       644810     185535 
2024         5459       1627