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         2986       1055 
1997         1890        652 
1998        22325       9434 
1999        13588       5214 
2000        38760      16029 
2001        39560      15370 
2002        32095      14248 
2003        58042      24146 
2004        46587      17875 
2005        81896      25205 
2006       105550      33867 
2007       192766      59547 
2008       114235      32667 
2009        94273      26561 
2010       117615      32509 
2011       160352      44459 
2012       151569      41993 
2013       224179      63853 
2014       568605     144860 
2015       800383     209634 
2016       666107     172787 
2017       558403     150990 
2018       355983      99985 
2019       871917     212882 
2020       624530     158998 
2021       842952     200454 
2022       628660     179935 
2023       564530     161456 
2024       630724     181602 
2025       171878      48980