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          743        301 
1993         1308        487 
1994         1684        618 
1995         3081       1075 
1996         2980       1053 
1997         1866        644 
1998        21954       9309 
1999        13560       5202 
2000        38678      15990 
2001        39480      15337 
2002        47256      19293 
2003        57821      24059 
2004        46405      17804 
2005        81570      25109 
2006       105237      33773 
2007       192117      59372 
2008       112826      32296 
2009        93535      26358 
2010       133287      36266 
2011       158703      44014 
2012       149974      41553 
2013       222095      63271 
2014       565717     144122 
2015       798676     210122 
2016       659240     171255 
2017       554722     150189 
2018       352987      99166 
2019       866442     211510 
2020       619458     157689 
2021       834822     198246 
2022       623077     178343 
2023       560554     160332 
2024       621613     179069 
2025       206558      59027