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         3096       1080 
1996         2980       1053 
1997         1869        645 
1998        22164       9380 
1999        13578       5209 
2000        38750      16022 
2001        39526      15356 
2002        31208      13948 
2003        57950      24112 
2004        46529      17853 
2005        81765      25167 
2006       105420      33828 
2007       192519      59481 
2008       113725      32535 
2009        94032      26494 
2010       120885      33294 
2011       159754      44297 
2012       151023      41842 
2013       223541      63672 
2014       568792     144906 
2015       809928     212330 
2016       664557     172391 
2017       557688     150786 
2018       354880      99676 
2019       870450     212481 
2020       622887     158587 
2021       840901     199906 
2022       626800     179403 
2023       562865     160976 
2024       626769     180500 
2025       183026      52055