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          219         78 
1991          864        309 
1992          675        277 
1993         1222        458 
1994         1565        583 
1995         2697        947 
1996         2802        992 
1997         2771        944 
1998        24401       8713 
1999        13179       5023 
2000        37215      15314 
2001        42247      16612 
2002        35780      15312 
2003        58462      23918 
2004        46001      17512 
2005       308696     138863 
2006       335266     149503 
2007       195038      60274 
2008       111867      31838 
2009        92675      25878 
2010       140876      37495 
2011       149734      40711 
2012       177320      38821 
2013       233832      59034 
2014       531151     130461 
2015       756350     197043 
2016       626577     161707 
2017       525396     142823 
2018       313386      88572 
2019       821675     201390 
2020       543102     137728 
2021       737255     172801 
2022       571285     163745 
2023       522108     149537 
2024       566078     162668 
2025       547930     155243 
2026       238633      50094