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         3084       1076 
1996         2980       1053 
1997         1866        644 
1998        21989       9321 
1999        13562       5203 
2000        38682      15992 
2001        39480      15337 
2002        47903      19505 
2003        57827      24062 
2004        46407      17805 
2005        81580      25112 
2006       105260      33779 
2007       192157      59383 
2008       112928      32324 
2009        93582      26371 
2010       133328      36278 
2011       158814      44045 
2012       150080      41582 
2013       222225      63308 
2014       565998     144194 
2015       798419     210029 
2016       658944     171148 
2017       554412     150084 
2018       353280      99249 
2019       866709     211587 
2020       619700     157756 
2021       835292     198380 
2022       623358     178423 
2023       560713     160378 
2024       622027     179180 
2025       207664      59316