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         3102       1082 
1996         2986       1055 
1997         1896        654 
1998        22333       9437 
1999        13606       5222 
2000        38813      16052 
2001        39580      15379 
2002        30989      13883 
2003        58115      24176 
2004        46644      17898 
2005        81993      25233 
2006       105668      33903 
2007       193123      59644 
2008       114718      32795 
2009        94584      26647 
2010       113824      31606 
2011       160926      44618 
2012       155010      43098 
2013       227841      65031 
2014       572154     146013 
2015       801335     209930 
2016       670626     174209 
2017       562797     152374 
2018       362018     101806 
2019       875356     213832 
2020       626156     159445 
2021       845349     201100 
2022       630070     180344 
2023       566486     161995 
2024       631894     181930 
2025       136971      38769