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         1746        640 
1995         3291       1145 
1996         3264       1149 
1997         2288        782 
1998        23093       9743 
1999        14418       5527 
2000        39980      16576 
2001        40802      15894 
2002        32045      14322 
2003        59816      24845 
2004        47317      18155 
2005        83087      25564 
2006       107128      34329 
2007       196470      60541 
2008       118099      33703 
2009        97353      27406 
2010       111939      31194 
2011       165715      45913 
2012       156677      43384 
2013       231415      65866 
2014       575330     146736 
2015       751085     196519 
2016       670045     173492 
2017       571417     154348 
2018       368033     103275 
2019       890871     217625 
2020       643287     163989 
2021       863222     205655 
2022       640106     183218 
2023       580146     166084 
2024       511785     147949