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        22007       9327 
1999        13562       5203 
2000        38682      15992 
2001        39480      15337 
2002        48425      19677 
2003        57829      24063 
2004        46405      17804 
2005        81583      25113 
2006       105269      33782 
2007       192183      59390 
2008       112940      32327 
2009        93586      26372 
2010       133340      36281 
2011       158833      44050 
2012       150104      41589 
2013       222271      63321 
2014       566020     144201 
2015       798316     210001 
2016       658743     171087 
2017       554374     150068 
2018       353333      99264 
2019       866850     211626 
2020       619773     157776 
2021       835434     198421 
2022       623457     178452 
2023       560741     160387 
2024       622121     179206 
2025       205596      58701