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          477        181 
1992          755        305 
1993         1339        498 
1994         1706        626 
1995         3156       1100 
1996         3022       1068 
1997         2018        695 
1998        22657       9568 
1999        13886       5326 
2000        39305      16273 
2001        40039      15575 
2002        31411      14071 
2003        58771      24445 
2004        47004      18037 
2005        82609      25419 
2006       106389      34113 
2007       194540      60028 
2008       116476      33264 
2009        95999      27033 
2010       110673      30867 
2011       163398      45287 
2012       154575      42815 
2013       227619      64809 
2014       558300     142753 
2015       766969     201412 
2016       663188     172042 
2017       564966     152728 
2018       362495     101780 
2019       881220     215219 
2020       634224     161581 
2021       854751     203514 
2022       635874     182023 
2023       572328     163867 
2024       642903     185148 
2025        49959      14383