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         2983       1054 
1997         1872        646 
1998        22259       9412 
1999        13582       5211 
2000        38758      16026 
2001        39542      15363 
2002        31233      13958 
2003        57985      24126 
2004        46558      17864 
2005        81824      25185 
2006       105475      33845 
2007       192629      59510 
2008       113982      32601 
2009        94154      26528 
2010       120998      33324 
2011       159997      44364 
2012       151224      41897 
2013       223713      63721 
2014       569112     144994 
2015       805696     211166 
2016       664896     172476 
2017       557939     150860 
2018       355248      99781 
2019       871051     212628 
2020       623458     158738 
2021       841730     200129 
2022       627469     179593 
2023       563244     161083 
2024       627480     180694 
2025       169382      48264