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         1692        621 
1995         3114       1086 
1996         3008       1063 
1997         1961        676 
1998        22346       9443 
1999        13622       5228 
2000        38930      16105 
2001        39700      15433 
2002        31151      13956 
2003        58376      24282 
2004        46880      17991 
2005        82414      25358 
2006       106126      34036 
2007       194126      59916 
2008       115934      33117 
2009        95532      26910 
2010       110179      30736 
2011       162613      45075 
2012       153941      42644 
2013       226654      64539 
2014       564843     144192 
2015       785999     205907 
2016       664319     172363 
2017       562407     152131 
2018       360726     101297 
2019       878638     214561 
2020       631938     161009 
2021       852287     202921 
2022       634396     181596 
2023       573479     163976 
2024       640213     184357 
2025        65375      18640