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        14416       5526 
2000        39959      16567 
2001        40717      15862 
2002        34331      15082 
2003        59740      24815 
2004        47276      18140 
2005        82988      25534 
2006       107015      34295 
2007       196220      60475 
2008       117888      33646 
2009        97170      27356 
2010       111752      31147 
2011       165383      45822 
2012       156430      43319 
2013       230798      65691 
2014       574527     146533 
2015       749071     196064 
2016       668729     173179 
2017       570395     154078 
2018       367262     103062 
2019       889546     217294 
2020       653731     166193 
2021       861992     205337 
2022       639174     182953 
2023       578805     165674 
2024       509601     147312