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        38933      16106 
2001        39700      15433 
2002        31155      13958 
2003        58379      24283 
2004        46884      17993 
2005        82418      25359 
2006       106126      34036 
2007       194138      59919 
2008       115969      33128 
2009        95543      26913 
2010       110207      30743 
2011       162625      45078 
2012       153952      42647 
2013       226693      64550 
2014       563656     143895 
2015       784461     205508 
2016       664231     172332 
2017       562514     152157 
2018       360775     101310 
2019       878707     214578 
2020       632052     161037 
2021       852360     202941 
2022       634451     181613 
2023       573555     163998 
2024       640355     184396 
2025        66245      18863