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         1308        487 
1994         1686        619 
1995         3099       1081 
1996         2986       1055 
1997         1890        652 
1998        22330       9436 
1999        13602       5220 
2000        38801      16047 
2001        39578      15378 
2002        30984      13881 
2003        58085      24163 
2004        46629      17891 
2005        81964      25224 
2006       105621      33889 
2007       193033      59619 
2008       114561      32754 
2009        94488      26621 
2010       113785      31596 
2011       160730      44565 
2012       154802      43043 
2013       227726      65001 
2014       572149     145995 
2015       801454     209972 
2016       671194     174364 
2017       562580     152307 
2018       361621     101696 
2019       874734     213701 
2020       625742     159332 
2021       844603     200890 
2022       629678     180232 
2023       566083     161875 
2024       631800     181903 
2025       146554      41626