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          743        301 
1993         1308        487 
1994         1684        618 
1995         3081       1075 
1996         2980       1053 
1997         1866        644 
1998        21906       9293 
1999        13560       5202 
2000        38674      15988 
2001        39480      15337 
2002        35028      15217 
2003        57819      24058 
2004        46402      17803 
2005        81567      25108 
2006       105233      33772 
2007       192105      59369 
2008       112810      32292 
2009        93523      26355 
2010       133286      36268 
2011       158690      44010 
2012       149935      41542 
2013       222067      63263 
2014       565643     144103 
2015       798649     210122 
2016       659631     171378 
2017       555122     150291 
2018       352958      99158 
2019       866285     211480 
2020       619443     157686 
2021       834531     198195 
2022       622971     178313 
2023       560476     160309 
2024       621500     179037 
2025       206317      58961