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         2885       1009 
1996         2886       1021 
1997         1784        618 
1998        21445       9125 
1999        12851       4953 
2000        37852      15630 
2001        39053      15139 
2002        34793      15079 
2003        56568      23531 
2004        45033      17312 
2005        79520      24504 
2006       102388      32939 
2007       186549      57879 
2008       104451      30050 
2009        87965      24865 
2010       140429      37773 
2011       148321      41209 
2012       139131      38616 
2013       212835      60709 
2014       540141     137441 
2015       796144     209581 
2016       633565     163774 
2017       545287     147714 
2018       333833      93906 
2019       845659     206652 
2020       583954     147931 
2021       794316     187673 
2022       603029     172636 
2023       543478     155531 
2024       599595     172290 
2025       568158     162537