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          471        179 
1992          749        303 
1993         1308        487 
1994         1686        619 
1995         3108       1084 
1996         2989       1056 
1997         1905        657 
1998        22340       9440 
1999        13611       5224 
2000        38844      16065 
2001        39622      15398 
2002        31019      13896 
2003        58190      24205 
2004        46704      17922 
2005        82094      25263 
2006       105788      33937 
2007       193381      59714 
2008       115080      32890 
2009        94837      26716 
2010       114064      31668 
2011       161366      44737 
2012       152633      42283 
2013       225208      64141 
2014       569171     145040 
2015       798693     209165 
2016       664109     172228 
2017       560087     151472 
2018       358054     100554 
2019       874888     213635 
2020       629294     160188 
2021       847154     201585 
2022       631323     180711 
2023       569034     162636 
2024       633959     182521 
2025       125106      35669