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         3892       1347 
1996         3578       1257 
1997         2331        795 
1998        23280       9815 
1999        14556       5583 
2000        40557      16833 
2001        45761      17606 
2002        32638      14591 
2003        61552      25510 
2004        48301      18527 
2005        86128      26469 
2006       111552      35627 
2007       205612      63005 
2008       126550      35996 
2009       103136      28969 
2010       119716      33226 
2011       179760      49707 
2012       166972      46204 
2013       258689      73452 
2014       643960     164230 
2015       746977     198231 
2016       574150     153247 
2017       611235     163799 
2018       405618     113666 
2019       934572     228168 
2020       697103     179002 
2021       904979     216945 
2022       673323     192612 
2023       611940     176176 
2024       159845      45638