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         2802        992 
1997         2768        943 
1998        24396       8711 
1999        13179       5023 
2000        37204      15309 
2001        42226      16605 
2002        35773      15309 
2003        58447      23912 
2004        45992      17508 
2005       308578     138817 
2006       335227     149488 
2007       194996      60264 
2008       111840      31831 
2009        92569      25848 
2010       140802      37476 
2011       149680      40695 
2012       177255      38803 
2013       233664      58986 
2014       531037     130432 
2015       756241     197021 
2016       626584     161711 
2017       525321     142810 
2018       313232      88534 
2019       821438     201324 
2020       543037     137710 
2021       737083     172750 
2022       571003     163674 
2023       521921     149486 
2024       565999     162646 
2025       547790     155204 
2026       247321      52637