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          532        200 
1992          936        367 
1993         1669        610 
1994         2333        842 
1995         4424       1527 
1996         3602       1265 
1997         2337        797 
1998        23334       9837 
1999        14619       5610 
2000        40754      16924 
2001        41820      16315 
2002        32996      14732 
2003        62050      25718 
2004        48721      18694 
2005        87138      26759 
2006       112906      36023 
2007       207874      63623 
2008       128906      36628 
2009       104722      29402 
2010       121728      33763 
2011       183454      50715 
2012       170118      47059 
2013       265385      75252 
2014       661447     168662 
2015       773842     205029 
2016       577011     154230 
2017       585308     157407 
2018       407012     114180 
2019       925382     225941 
2020       713702     183204 
2021       927638     223133 
2022       695977     198915 
2023       632378     181950 
2024        66220      19146