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          471        179 
1992          746        302 
1993         1308        487 
1994         1684        618 
1995         3093       1079 
1996         2980       1053 
1997         1866        644 
1998        22081       9352 
1999        13572       5207 
2000        38717      16006 
2001        39502      15347 
2002        49340      19990 
2003        57868      24079 
2004        46449      17821 
2005        81672      25139 
2006       105311      33795 
2007       192283      59417 
2008       113206      32399 
2009        93733      26411 
2010       129420      35340 
2011       159126      44129 
2012       150423      41679 
2013       222771      63459 
2014       566911     144431 
2015       797630     209774 
2016       658255     170924 
2017       554882     150188 
2018       353778      99384 
2019       867686     211795 
2020       620885     158048 
2021       837450     198994 
2022       624538     178756 
2023       561577     160618 
2024       623539     179601 
2025       189747      54185