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         4380       1512 
1996         3593       1262 
1997         2334        796 
1998        23314       9828 
1999        14588       5596 
2000        40643      16874 
2001        41655      16246 
2002        32788      14652 
2003        61716      25579 
2004        48484      18601 
2005        86567      26594 
2006       112079      35782 
2007       206680      63299 
2008       127581      36271 
2009       103853      29164 
2010       120504      33437 
2011       181417      50159 
2012       168450      46602 
2013       262004      74306 
2014       649481     165633 
2015       759381     201401 
2016       579105     154490 
2017       609913     162953 
2018       407139     114104 
2019       931394     227082 
2020       702281     180372 
2021       940171     224607 
2022       680670     194685 
2023       618079     177891 
2024       138193      39603