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          468        178 
1992          740        300 
1993         1296        483 
1994         1661        610 
1995         3000       1048 
1996         2953       1044 
1997         1822        631 
1998        21596       9189 
1999        13146       5057 
2000        38438      15889 
2001        39264      15251 
2002        31566      14044 
2003        57480      23926 
2004        46106      17699 
2005        80879      24914 
2006       104340      33518 
2007       190888      59045 
2008       111238      31876 
2009        92233      26012 
2010       144386      38804 
2011       156227      43359 
2012       147585      40911 
2013       219230      62489 
2014       562984     143491 
2015       798931     210221 
2016       656458     170590 
2017       552253     149529 
2018       349394      98179 
2019       860820     210144 
2020       613803     156204 
2021       825631     195970 
2022       617304     176707 
2023       556337     159159 
2024       613101     176640 
2025       288972      83126