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         3087       1077 
1996         2980       1053 
1997         1866        644 
1998        22028       9334 
1999        13565       5204 
2000        38690      15995 
2001        39485      15339 
2002        49315      19980 
2003        57843      24069 
2004        46425      17811 
2005        81598      25117 
2006       105279      33785 
2007       192224      59401 
2008       113002      32344 
2009        93636      26385 
2010       129755      35420 
2011       158916      44073 
2012       150171      41609 
2013       222383      63354 
2014       566188     144248 
2015       798090     209936 
2016       658440     171003 
2017       554392     150054 
2018       353464      99305 
2019       866909     211640 
2020       619958     157826 
2021       836341     198673 
2022       623761     178537 
2023       560848     160419 
2024       622339     179268 
2025       200837      57304