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        38745      16020 
2001        39522      15354 
2002        31206      13947 
2003        57944      24109 
2004        46521      17849 
2005        81754      25164 
2006       105412      33826 
2007       192485      59472 
2008       113651      32516 
2009        94000      26485 
2010       120859      33287 
2011       159694      44281 
2012       150943      41821 
2013       223483      63657 
2014       568647     144864 
2015       810458     212473 
2016       664435     172361 
2017       557574     150752 
2018       354798      99652 
2019       870285     212435 
2020       622705     158534 
2021       840521     199797 
2022       626608     179346 
2023       562741     160940 
2024       626616     180456 
2025       184357      52488