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          489        185 
1992          767        309 
1993         1356        504 
1994         1746        640 
1995         3285       1143 
1996         3162       1115 
1997         2288        782 
1998        23078       9736 
1999        14410       5524 
2000        39958      16566 
2001        40709      15859 
2002        33728      14880 
2003        59681      24793 
2004        47267      18137 
2005        82947      25521 
2006       106986      34287 
2007       196004      60416 
2008       117741      33606 
2009        97044      27320 
2010       111636      31117 
2011       165165      45763 
2012       156261      43274 
2013       230474      65601 
2014       571676     145855 
2015       744761     195048 
2016       667676     172923 
2017       569803     153933 
2018       366717     102913 
2019       888747     217088 
2020       640677     163274 
2021       861091     205111 
2022       638811     182849 
2023       577972     165437 
2024       519089     150248