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        22087       9354 
1999        13572       5207 
2000        38719      16007 
2001        39504      15348 
2002        31214      13948 
2003        57873      24081 
2004        46454      17823 
2005        81676      25140 
2006       105325      33799 
2007       192299      59421 
2008       113250      32411 
2009        93766      26420 
2010       129450      35348 
2011       159165      44140 
2012       150447      41685 
2013       222824      63473 
2014       567048     144469 
2015       797518     209738 
2016       658363     170954 
2017       554952     150207 
2018       353798      99388 
2019       867683     211793 
2020       620999     158080 
2021       837654     199051 
2022       624656     178789 
2023       561752     160663 
2024       623612     179623 
2025       188142      53714