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          489        185 
1992          767        309 
1993         1356        504 
1994         1746        640 
1995         3285       1143 
1996         3162       1115 
1997         2288        782 
1998        23078       9736 
1999        14410       5524 
2000        39958      16566 
2001        40709      15859 
2002        31961      14291 
2003        59681      24793 
2004        47267      18137 
2005        82944      25520 
2006       106986      34287 
2007       196000      60415 
2008       117741      33606 
2009        97036      27318 
2010       111636      31117 
2011       165161      45762 
2012       156250      43271 
2013       230468      65599 
2014       571660     145850 
2015       744734     195040 
2016       667672     172922 
2017       569790     153929 
2018       366696     102907 
2019       888727     217082 
2020       640601     163256 
2021       861043     205098 
2022       638811     182849 
2023       577876     165408 
2024       519001     150221