Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           14          7 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          216         77 
1991          861        308 
1992          675        277 
1993         1222        458 
1994         1581        587 
1995         2705        950 
1996         2799        991 
1997         2768        943 
1998        24394       8710 
1999        13179       5023 
2000        37204      15309 
2001        42224      16604 
2002        35770      15308 
2003        58440      23909 
2004        45988      17507 
2005       308559     138812 
2006       335215     149483 
2007       194988      60262 
2008       111836      31830 
2009        92528      25836 
2010       140785      37471 
2011       149668      40692 
2012       177222      38794 
2013       233635      58978 
2014       530951     130410 
2015       756141     196994 
2016       626575     161706 
2017       525261     142792 
2018       313159      88514 
2019       821408     201318 
2020       543076     137717 
2021       736973     172720 
2022       570891     163642 
2023       521907     149482 
2024       565976     162639 
2025       547673     155171 
2026       248770      53059