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        14621       5611 
2000        40776      16933 
2001        41844      16326 
2002        33031      14747 
2003        62088      25739 
2004        48770      18714 
2005        87200      26777 
2006       113054      36066 
2007       208073      63677 
2008       129091      36678 
2009       104853      29438 
2010       121889      33805 
2011       183744      50793 
2012       170365      47127 
2013       265852      75384 
2014       662269     168874 
2015       774463     205198 
2016       576372     154125 
2017       576843     156022 
2018       407770     114393 
2019       926254     226172 
2020       714401     183393 
2021       927646     223125 
2022       696952     199191 
2023       632987     182133 
2024        59372      17284