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         2339        844 
1995         4430       1529 
1996         3605       1266 
1997         2334        796 
1998        23340       9839 
1999        14628       5614 
2000        40801      16944 
2001        41885      16344 
2002        33096      14773 
2003        62173      25771 
2004        48836      18741 
2005        87337      26813 
2006       113222      36119 
2007       208209      63715 
2008       129369      36754 
2009       105042      29491 
2010       122130      33870 
2011       184139      50899 
2012       170680      47213 
2013       266374      75530 
2014       663181     169110 
2015       775631     205503 
2016       574731     153811 
2017       566413     154438 
2018       407354     114288 
2019       925329     225931 
2020       715204     183642 
2021       943614     226447 
2022       690478     197520 
2023       634632     182606 
2024        48530      14069