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         4427       1528 
1996         3605       1266 
1997         2334        796 
1998        23334       9837 
1999        14623       5612 
2000        40776      16933 
2001        41854      16330 
2002        33031      14747 
2003        62117      25751 
2004        48775      18716 
2005        87204      26778 
2006       113059      36068 
2007       208087      63681 
2008       129111      36683 
2009       104869      29442 
2010       121914      33812 
2011       183784      50804 
2012       170388      47133 
2013       265890      75395 
2014       662343     168895 
2015       774525     205216 
2016       576149     154079 
2017       576167     155875 
2018       407649     114359 
2019       927047     226313 
2020       714463     183410 
2021       927928     223171 
2022       697039     199217 
2023       633305     182223 
2024        59361      17280