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        14628       5614 
2000        40797      16942 
2001        41883      16343 
2002        33090      14771 
2003        62170      25770 
2004        48836      18741 
2005        87337      26813 
2006       113215      36117 
2007       208201      63713 
2008       129359      36751 
2009       105035      29489 
2010       122127      33869 
2011       184127      50896 
2012       170653      47206 
2013       266336      75520 
2014       663059     169079 
2015       775480     205465 
2016       574785     153816 
2017       568820     154841 
2018       407379     114297 
2019       926028     226019 
2020       715274     183636 
2021       942117     225953 
2022       690442     197510 
2023       634395     182536 
2024        48514      14064