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          492        186 
1992          767        309 
1993         1356        504 
1994         1749        641 
1995         3297       1147 
1996         3312       1165 
1997         2291        783 
1998        23113       9750 
1999        14429       5531 
2000        40001      16586 
2001        40848      15913 
2002        32076      14335 
2003        59916      24882 
2004        47339      18164 
2005        83167      25588 
2006       107287      34375 
2007       196974      60675 
2008       118516      33816 
2009        97586      27469 
2010       112309      31287 
2011       166366      46086 
2012       157047      43486 
2013       232461      66155 
2014       576219     146968 
2015       754271     197319 
2016       671219     173785 
2017       572551     154655 
2018       369403     103659 
2019       893147     218234 
2020       645011     164466 
2021       864683     206067 
2022       640891     183490 
2023       585810     167544 
2024       514415     148651