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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         3907       1352 
1996         3578       1257 
1997         2331        795 
1998        23285       9817 
1999        14561       5585 
2000        40559      16834 
2001        45761      17606 
2002        32641      14592 
2003        61565      25515 
2004        48307      18530 
2005        86150      26475 
2006       111590      35639 
2007       205640      63012 
2008       126591      36007 
2009       103151      28973 
2010       119763      33238 
2011       179827      49726 
2012       167012      46215 
2013       258745      73469 
2014       644156     164284 
2015       748400     198629 
2016       574878     153450 
2017       611576     163896 
2018       405767     113709 
2019       934305     228060 
2020       697232     179034 
2021       905143     216988 
2022       673649     192704 
2023       612771     176405 
2024       160489      45775