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          746        302 
1993         1308        487 
1994         1684        618 
1995         3096       1080 
1996         2980       1053 
1997         1869        645 
1998        22230       9402 
1999        13580       5210 
2000        38754      16024 
2001        39538      15361 
2002        31218      13952 
2003        57963      24117 
2004        46547      17860 
2005        81807      25179 
2006       105428      33831 
2007       192542      59487 
2008       113822      32559 
2009        94071      26505 
2010       120913      33301 
2011       159839      44320 
2012       151103      41864 
2013       223637      63699 
2014       568911     144937 
2015       807738     211732 
2016       664612     172404 
2017       557740     150802 
2018       354991      99709 
2019       870728     212551 
2020       623195     158658 
2021       841268     200001 
2022       627115     179494 
2023       562976     161009 
2024       627332     180653 
2025       173891      49410