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        13562       5203 
2000        38685      15993 
2001        39485      15339 
2002        62185      24188 
2003        57837      24067 
2004        46413      17807 
2005        81591      25115 
2006       105279      33785 
2007       192210      59397 
2008       112973      32336 
2009        93605      26377 
2010       133353      36284 
2011       158867      44060 
2012       150141      41599 
2013       222324      63336 
2014       566128     144232 
2015       798157     209953 
2016       658481     171019 
2017       554281     150034 
2018       353372      99277 
2019       866800     211610 
2020       619831     157792 
2021       836055     198595 
2022       623585     178490 
2023       560812     160408 
2024       622271     179248 
2025       205752      58719