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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4425       1527 
1996         3593       1262 
1997         2337        797 
1998        23325       9833 
1999        14598       5601 
2000        40668      16886 
2001        41699      16265 
2002        32833      14669 
2003        61801      25614 
2004        48550      18628 
2005        86716      26638 
2006       112265      35838 
2007       207001      63386 
2008       127876      36350 
2009       104136      29240 
2010       120864      33533 
2011       182091      50346 
2012       168974      46747 
2013       262981      74575 
2014       654185     166806 
2015       762186     202121 
2016       579413     154538 
2017       604832     161472 
2018       406267     113912 
2019       933080     227519 
2020       709514     182088 
2021       921324     221553 
2022       688875     196978 
2023       621068     178731 
2024       120204      34365