Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           12          6 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          216         77 
1991          856        306 
1992          656        270 
1993         1176        442 
1994         1484        554 
1995         2353        831 
1996         2617        929 
1997         2492        851 
1998        23916       8544 
1999        12818       4889 
2000        36298      14905 
2001        41399      16256 
2002        34952      14954 
2003        56868      23299 
2004        44778      17055 
2005       302786     136461 
2006       330339     147530 
2007       191583      59364 
2008       107485      30672 
2009        87949      24615 
2010       135652      36137 
2011       142471      38769 
2012       170005      36849 
2013       223902      56324 
2014       471071     116888 
2015       708847     185388 
2016       598879     154766 
2017       503146     136784 
2018       300581      85009 
2019       802180     196473 
2020       525593     133169 
2021       707636     165523 
2022       549484     157620 
2023       508813     145778 
2024       548910     157777 
2025       523649     148905 
2026       368589      87731