Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          477        181 
1992          755        305 
1993         1339        498 
1994         1706        626 
1995         3156       1100 
1996         3022       1068 
1997         2018        695 
1998        22657       9568 
1999        13886       5326 
2000        39300      16271 
2001        40039      15575 
2002        31412      14071 
2003        58771      24444 
2004        47001      18036 
2005        82596      25415 
2006       106364      34106 
2007       194514      60021 
2008       116450      33257 
2009        95965      27024 
2010       110653      30862 
2011       163334      45270 
2012       154522      42801 
2013       227544      64788 
2014       558494     142795 
2015       768853     201859 
2016       663681     172173 
2017       564849     152696 
2018       362366     101745 
2019       881040     215167 
2020       634007     161520 
2021       854615     203476 
2022       635739     181985 
2023       572081     163797 
2024       642616     185065 
2025        50468      14506