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          503        190 
1992          936        367 
1993         1666        609 
1994         2326        839 
1995         3521       1223 
1996         3576       1256 
1997         2329        794 
1998        23260       9807 
1999        14524       5569 
2000        40476      16796 
2001        43052      16694 
2002        32496      14526 
2003        61248      25391 
2004        47983      18402 
2005        85435      26267 
2006       110904      35437 
2007       204126      62598 
2008       125308      35662 
2009       101942      28646 
2010       118409      32888 
2011       177686      49139 
2012       165052      45609 
2013       256000      72408 
2014       641853     162730 
2015       741581     196217 
2016       570284     152122 
2017       605242     162801 
2018       397647     111241 
2019       938708     229798 
2020       688856     176564 
2021       895760     214447 
2022       664930     190188 
2023       604116     173944 
2024       212290      61348