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          746        302 
1993         1308        487 
1994         1684        618 
1995         3099       1081 
1996         2983       1054 
1997         1884        650 
1998        22325       9434 
1999        13588       5214 
2000        38760      16029 
2001        39558      15369 
2002        32082      14243 
2003        58031      24141 
2004        46587      17875 
2005        81864      25196 
2006       105526      33860 
2007       192710      59531 
2008       114121      32637 
2009        94224      26547 
2010       117590      32502 
2011       160246      44430 
2012       151449      41960 
2013       223969      63793 
2014       568763     144897 
2015       800661     209723 
2016       665867     172723 
2017       558281     150953 
2018       355695      99901 
2019       871485     212758 
2020       624140     158889 
2021       842499     200326 
2022       628251     179817 
2023       564133     161339 
2024       629379     181219 
2025       171409      48813