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          468        178 
1992          740        300 
1993         1296        483 
1994         1661        610 
1995         3000       1048 
1996         2956       1045 
1997         1822        631 
1998        21596       9189 
1999        13155       5060 
2000        38443      15891 
2001        39270      15254 
2002        31586      14051 
2003        57482      23927 
2004        46111      17701 
2005        80892      24918 
2006       104354      33522 
2007       190902      59049 
2008       111260      31882 
2009        92254      26018 
2010       144433      38816 
2011       156262      43369 
2012       147609      40917 
2013       219296      62507 
2014       563109     143520 
2015       798405     210149 
2016       656403     170583 
2017       552529     149603 
2018       349604      98232 
2019       860836     210149 
2020       613858     156220 
2021       825853     196037 
2022       617459     176755 
2023       556532     159212 
2024       613221     176675 
2025       287264      82578