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        22102       9359 
1999        13572       5207 
2000        38721      16008 
2001        39507      15349 
2002        31217      13949 
2003        57873      24081 
2004        46457      17824 
2005        81676      25140 
2006       105325      33799 
2007       192322      59427 
2008       113273      32417 
2009        93788      26427 
2010       129472      35356 
2011       159187      44146 
2012       150470      41691 
2013       222855      63482 
2014       567043     144468 
2015       797643     209729 
2016       659335     171199 
2017       555434     150314 
2018       354019      99447 
2019       868171     211890 
2020       621041     158093 
2021       837744     199078 
2022       624771     178821 
2023       561780     160671 
2024       623819     179682 
2025       188051      53694