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         3285       1143 
1996         3171       1118 
1997         2288        782 
1998        23084       9739 
1999        14413       5525 
2000        39959      16567 
2001        40717      15862 
2002        34331      15082 
2003        59718      24807 
2004        47273      18139 
2005        82985      25533 
2006       107011      34294 
2007       196156      60458 
2008       117837      33632 
2009        97153      27351 
2010       111740      31144 
2011       165340      45810 
2012       156380      43306 
2013       230732      65671 
2014       574394     146499 
2015       748925     196025 
2016       668600     173143 
2017       570223     154033 
2018       367132     103026 
2019       889356     217241 
2020       641400     163474 
2021       861562     205244 
2022       639075     182925 
2023       578573     165609 
2024       510565     147647