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         2894       1012 
1996         2895       1024 
1997         1784        618 
1998        21448       9126 
1999        12860       4956 
2000        37958      15675 
2001        39104      15162 
2002        35428      15298 
2003        57929      24000 
2004        45232      17381 
2005        79807      24592 
2006       102734      33041 
2007       187189      58051 
2008       105839      30425 
2009        88798      25088 
2010       141113      37955 
2011       149865      41626 
2012       140734      39052 
2013       214210      61086 
2014       544378     138547 
2015       795862     209459 
2016       642169     166511 
2017       542675     146931 
2018       336869      94721 
2019       848461     207182 
2020       589488     149496 
2021       800244     189248 
2022       606359     173586 
2023       546391     156362 
2024       604266     173619 
2025       534256     152181