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         4398       1518 
1996         3593       1262 
1997         2334        796 
1998        23319       9830 
1999        14588       5596 
2000        40643      16874 
2001        41657      16247 
2002        32787      14652 
2003        61718      25580 
2004        48488      18603 
2005        86572      26595 
2006       112079      35782 
2007       206701      63305 
2008       127581      36271 
2009       103853      29164 
2010       120535      33446 
2011       181476      50175 
2012       168520      46622 
2013       262175      74349 
2014       652733     166426 
2015       759424     201414 
2016       579266     154524 
2017       609173     162821 
2018       407132     114102 
2019       931160     227032 
2020       702312     180371 
2021       911373     218756 
2022       680942     194765 
2023       618136     177903 
2024       138220      39610