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        21933       9302 
1999        13560       5202 
2000        38676      15989 
2001        39480      15337 
2002        35028      15217 
2003        57819      24058 
2004        46402      17803 
2005        81570      25109 
2006       105233      33772 
2007       192109      59370 
2008       112810      32292 
2009        93527      26356 
2010       133276      36264 
2011       158693      44011 
2012       149941      41544 
2013       222077      63266 
2014       565643     144103 
2015       798633     210117 
2016       659476     171322 
2017       554989     150254 
2018       352973      99162 
2019       866402     211496 
2020       619456     157689 
2021       834579     198209 
2022       623015     178326 
2023       560526     160324 
2024       621545     179049 
2025       206477      59007