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         3087       1077 
1996         2980       1053 
1997         1866        644 
1998        22057       9344 
1999        13570       5206 
2000        38712      16004 
2001        39496      15344 
2002        49330      19986 
2003        57855      24074 
2004        46447      17820 
2005        81632      25127 
2006       105300      33791 
2007       192234      59404 
2008       113146      32381 
2009        93702      26403 
2010       129780      35423 
2011       159048      44108 
2012       150314      41648 
2013       222592      63411 
2014       566600     144354 
2015       797476     209765 
2016       658108     170890 
2017       554671     150131 
2018       353707      99369 
2019       867308     211723 
2020       620325     157928 
2021       837064     198882 
2022       624206     178663 
2023       561233     160526 
2024       622900     179426 
2025       191483      54631