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        22159       9378 
1999        13578       5209 
2000        38743      16019 
2001        39522      15354 
2002        31266      13967 
2003        57937      24106 
2004        46505      17843 
2005        81740      25160 
2006       105397      33821 
2007       192456      59464 
2008       113597      32502 
2009        93919      26464 
2010       120826      33277 
2011       159580      44251 
2012       150811      41786 
2013       223387      63629 
2014       568446     144806 
2015       811209     212668 
2016       664296     172323 
2017       557285     150671 
2018       354608      99598 
2019       869998     212352 
2020       622377     158441 
2021       839843     199647 
2022       626284     179252 
2023       562585     160893 
2024       626074     180301 
2025       187643      53376