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        38725      16010 
2001        39507      15349 
2002        36819      15816 
2003        57879      24083 
2004        46461      17826 
2005        81694      25145 
2006       105328      33800 
2007       192340      59433 
2008       113307      32426 
2009        93803      26431 
2010       124175      34087 
2011       159235      44159 
2012       150497      41699 
2013       222942      63503 
2014       567628     144592 
2015       817742     214538 
2016       663577     172136 
2017       556720     150516 
2018       354022      99438 
2019       869220     212163 
2020       621501     158220 
2021       838157     199190 
2022       625137     178923 
2023       562093     160752 
2024       624634     179903 
2025       188761      53828