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          749        303 
1993         1313        489 
1994         1692        621 
1995         3117       1087 
1996         3008       1063 
1997         1961        676 
1998        22355       9446 
1999        13634       5232 
2000        38960      16118 
2001        39726      15444 
2002        31176      13968 
2003        58428      24303 
2004        46917      18005 
2005        82511      25389 
2006       106242      34070 
2007       194296      59961 
2008       116191      33188 
2009        95703      26955 
2010       110442      30804 
2011       162867      45145 
2012       154152      42701 
2013       227058      64652 
2014       562930     143701 
2015       780394     204561 
2016       664485     172384 
2017       563857     152442 
2018       361462     101499 
2019       879852     214860 
2020       632878     161265 
2021       853207     203169 
2022       635075     181794 
2023       574596     164285 
2024       642887     185136 
2025        63386      17778