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         1631        600 
1995         2897       1013 
1996         2895       1024 
1997         1784        618 
1998        21448       9126 
1999        12868       4959 
2000        37969      15680 
2001        39298      15231 
2002        33758      14734 
2003        56584      23554 
2004        45299      17405 
2005        79817      24595 
2006       102774      33054 
2007       187314      58085 
2008       106092      30493 
2009        88962      25132 
2010       141207      37980 
2011       150150      41704 
2012       141096      39149 
2013       214398      61139 
2014       545068     138738 
2015       794863     209181 
2016       644698     167380 
2017       542869     146968 
2018       337371      94858 
2019       848531     207164 
2020       589978     149630 
2021       801000     189460 
2022       606942     173746 
2023       546671     156439 
2024       605099     173843 
2025       508557     145058