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         3224       1135 
1997         2288        782 
1998        23086       9740 
1999        14416       5526 
2000        39968      16571 
2001        40776      15883 
2002        33646      14854 
2003        59783      24831 
2004        47293      18146 
2005        83020      25544 
2006       107051      34306 
2007       196332      60505 
2008       117962      33667 
2009        97233      27373 
2010       111820      31164 
2011       165499      45854 
2012       156538      43347 
2013       231028      65757 
2014       574825     146604 
2015       750129     196275 
2016       669483     173353 
2017       570893     154203 
2018       367621     103163 
2019       889992     217416 
2020       642193     163696 
2021       862383     205446 
2022       639486     183042 
2023       578721     165695 
2024       510009     147445