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          861        308 
1992          675        277 
1993         1222        458 
1994         1581        587 
1995         2705        950 
1996         2802        992 
1997         2768        943 
1998        24401       8713 
1999        13179       5023 
2000        37211      15312 
2001        42234      16608 
2002        35775      15310 
2003        58456      23916 
2004        45999      17511 
2005       308664     138849 
2006       335251     149498 
2007       195015      60269 
2008       111852      31834 
2009        92638      25867 
2010       140847      37488 
2011       149716      40706 
2012       177289      38812 
2013       233784      59021 
2014       531103     130448 
2015       756311     197033 
2016       626609     161714 
2017       525344     142809 
2018       313332      88559 
2019       821608     201372 
2020       543024     137708 
2021       737175     172777 
2022       571194     163727 
2023       522046     149519 
2024       566026     162653 
2025       547882     155229 
2026       242595      51239