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          471        179 
1992          749        303 
1993         1310        488 
1994         1686        619 
1995         3111       1085 
1996         2993       1058 
1997         1917        661 
1998        22337       9439 
1999        13620       5227 
2000        38856      16071 
2001        39642      15407 
2002        31041      13908 
2003        58217      24216 
2004        46728      17932 
2005        82127      25273 
2006       105870      33961 
2007       193506      59746 
2008       115239      32931 
2009        94960      26749 
2010       114161      31692 
2011       161520      44780 
2012       152820      42335 
2013       225423      64201 
2014       568787     144973 
2015       796534     208584 
2016       664275     172277 
2017       560466     151577 
2018       358454     100661 
2019       875468     213753 
2020       628197     159979 
2021       847908     201754 
2022       631817     180857 
2023       569618     162767 
2024       634911     182791 
2025       124953      35696