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         1869        645 
1998        22120       9365 
1999        13572       5207 
2000        38729      16012 
2001        39511      15351 
2002        31044      13891 
2003        57891      24087 
2004        46474      17831 
2005        81705      25148 
2006       105351      33807 
2007       192381      59444 
2008       113365      32441 
2009        93843      26442 
2010       124227      34100 
2011       159303      44178 
2012       150569      41719 
2013       223103      63548 
2014       567841     144642 
2015       814791     213683 
2016       663855     172199 
2017       556878     150555 
2018       354190      99483 
2019       869300     212166 
2020       621817     158286 
2021       838458     199276 
2022       625366     178990 
2023       562194     160781 
2024       624997     180002 
2025       190486      54294