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        40760      16927 
2001        41833      16321 
2002        33016      14740 
2003        62070      25727 
2004        48739      18701 
2005        87168      26767 
2006       112990      36048 
2007       207936      63639 
2008       128982      36649 
2009       104784      29419 
2010       121821      33787 
2011       183617      50760 
2012       170209      47084 
2013       265618      75317 
2014       661824     168760 
2015       774148     205114 
2016       576489     154154 
2017       578925     156304 
2018       407139     114214 
2019       925457     225981 
2020       714007     183303 
2021       934885     224637 
2022       696467     199053 
2023       632432     181971 
2024        61992      17997