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         1316        490 
1994         1692        621 
1995         3120       1088 
1996         3008       1063 
1997         1961        676 
1998        22385       9458 
1999        13667       5244 
2000        39029      16151 
2001        39794      15474 
2002        31223      13989 
2003        58505      24336 
2004        46936      18013 
2005        82575      25408 
2006       106324      34093 
2007       194439      60001 
2008       116348      33230 
2009        95880      27003 
2010       110583      30843 
2011       163188      45230 
2012       154374      42763 
2013       227376      64741 
2014       559504     142998 
2015       773676     203024 
2016       664676     172429 
2017       564581     152621 
2018       361967     101634 
2019       880617     215066 
2020       633583     161423 
2021       854270     203390 
2022       635563     181934 
2023       571731     163697 
2024       642140     184927 
2025        51705      14848