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          492        186 
1992          767        309 
1993         1356        504 
1994         1749        641 
1995         3303       1149 
1996         3327       1170 
1997         2291        783 
1998        23116       9751 
1999        14432       5532 
2000        40017      16594 
2001        40861      15919 
2002        32078      14336 
2003        59942      24893 
2004        47353      18169 
2005        83235      25608 
2006       107422      34415 
2007       197288      60760 
2008       118823      33900 
2009        97740      27511 
2010       112574      31356 
2011       166730      46182 
2012       157391      43580 
2013       233342      66397 
2014       576918     147155 
2015       756591     197890 
2016       672196     174039 
2017       573394     154878 
2018       370441     103950 
2019       894608     218638 
2020       646295     164801 
2021       865786     206367 
2022       641639     183704 
2023       585290     167428 
2024       497117     143520