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        37202      15308 
2001        42222      16603 
2002        35770      15308 
2003        58437      23908 
2004        45985      17506 
2005       308546     138807 
2006       335209     149480 
2007       194985      60261 
2008       111836      31830 
2009        92517      25833 
2010       140781      37470 
2011       149659      40689 
2012       177219      38793 
2013       233635      58978 
2014       530936     130406 
2015       756105     196986 
2016       626640     161722 
2017       525259     142792 
2018       313150      88511 
2019       821390     201313 
2020       543110     137725 
2021       736947     172713 
2022       570883     163640 
2023       521903     149481 
2024       565976     162639 
2025       547645     155163 
2026       249398      53258