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        22093       9356 
1999        13572       5207 
2000        38719      16007 
2001        39507      15349 
2002        31217      13949 
2003        57873      24081 
2004        46457      17824 
2005        81676      25140 
2006       105325      33799 
2007       192310      59424 
2008       113253      32412 
2009        93766      26420 
2010       129450      35348 
2011       159173      44142 
2012       150470      41691 
2013       222830      63475 
2014       567067     144474 
2015       797216     209649 
2016       658399     170961 
2017       554972     150212 
2018       353830      99397 
2019       867787     211821 
2020       621006     158081 
2021       837684     199060 
2022       624700     178801 
2023       561756     160664 
2024       623633     179630 
2025       188053      53695