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         3602       1265 
1997         2334        796 
1998        23334       9837 
1999        14621       5611 
2000        40764      16928 
2001        41839      16324 
2002        33021      14742 
2003        62066      25731 
2004        48754      18707 
2005        87186      26773 
2006       113022      36057 
2007       208018      63661 
2008       129053      36668 
2009       104827      29431 
2010       121848      33795 
2011       183719      50787 
2012       170299      47108 
2013       265749      75355 
2014       662176     168850 
2015       774356     205170 
2016       576594     154176 
2017       577975     156159 
2018       407750     114386 
2019       926424     226226 
2020       714323     183370 
2021       928568     223338 
2022       696817     199153 
2023       632823     182085 
2024        59530      17333