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         4425       1527 
1996         3593       1262 
1997         2337        797 
1998        23323       9832 
1999        14596       5600 
2000        40668      16886 
2001        41691      16261 
2002        32833      14669 
2003        61793      25611 
2004        48548      18627 
2005        86711      26636 
2006       112237      35830 
2007       206977      63380 
2008       127810      36332 
2009       104102      29231 
2010       120804      33517 
2011       182017      50326 
2012       168896      46725 
2013       262899      74551 
2014       654045     166770 
2015       761151     201874 
2016       579434     154533 
2017       605819     161727 
2018       406776     114020 
2019       932871     227446 
2020       708819     181933 
2021       921188     221514 
2022       688709     196929 
2023       620694     178628 
2024       121642      34783