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        24388       8708 
1999        13179       5023 
2000        37200      15307 
2001        42222      16603 
2002        35767      15307 
2003        58435      23907 
2004        45983      17505 
2005       308538     138805 
2006       335209     149480 
2007       194973      60258 
2008       111824      31827 
2009        92501      25828 
2010       140769      37467 
2011       149651      40687 
2012       177187      38784 
2013       233626      58975 
2014       530891     130394 
2015       756065     196975 
2016       626630     161719 
2017       525252     142790 
2018       313127      88505 
2019       821335     201303 
2020       543049     137709 
2021       736901     172700 
2022       570825     163622 
2023       521887     149476 
2024       565963     162635 
2025       547571     155140 
2026       248832      53124