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          444        170 
1992          721        293 
1993         1280        477 
1994         1628        599 
1995         2885       1009 
1996         2889       1022 
1997         1784        618 
1998        21444       9124 
1999        12854       4954 
2000        37864      15635 
2001        39055      15140 
2002        34800      15082 
2003        56575      23534 
2004        45059      17320 
2005        79540      24510 
2006       102426      32949 
2007       186589      57890 
2008       104661      30108 
2009        88114      24905 
2010       140590      37816 
2011       148503      41258 
2012       139349      38673 
2013       213082      60776 
2014       540318     137489 
2015       796272     209613 
2016       634105     163948 
2017       545096     147658 
2018       334045      93963 
2019       845951     206724 
2020       584263     148016 
2021       795047     187881 
2022       603317     172718 
2023       543698     155595 
2024       599870     172367 
2025       566841     162093