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        457 
1994         1593        587 
1995         2705        949 
1996         2802        993 
1997         2771        947 
1998        24404      10270 
1999        13179       5033 
2000        37215      15324 
2001        42247      16624 
2002        35780      15333 
2003        58465      23933 
2004        46001      17540 
2005       308708     138903 
2006       335270     149577 
2007       195042      60399 
2008       111871      32030 
2009        92678      26023 
2010       140880      37622 
2011       149734      40905 
2012       177333      38894 
2013       233842      59152 
2014       531163     130432 
2015       756237     197243 
2016       626520     161931 
2017       525393     142882 
2018       313423      88493 
2019       821694     201087 
2020       543068     137573 
2021       737265     172779 
2022       571333     163696 
2023       522108     149511 
2024       566081     162661 
2025       547938     154948 
2026       238258      49976