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          444        170 
1992          721        293 
1993         1280        477 
1994         1628        599 
1995         2891       1011 
1996         2889       1022 
1997         1784        618 
1998        21444       9124 
1999        12857       4955 
2000        37885      15645 
2001        39064      15144 
2002        34821      15092 
2003        56642      23560 
2004        45098      17333 
2005        79646      24542 
2006       102492      32969 
2007       186734      57930 
2008       104859      30160 
2009        88298      24954 
2010       140717      37850 
2011       148821      41340 
2012       139570      38735 
2013       213405      60865 
2014       541316     137747 
2015       796322     209615 
2016       635547     164330 
2017       544136     147359 
2018       335266      94299 
2019       846453     206833 
2020       586273     148576 
2021       796693     188316 
2022       604103     172937 
2023       544495     155822 
2024       601075     172714 
2025       570153     163015