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          503        190 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         3808       1319 
1996         3578       1257 
1997         2335        796 
1998        23277       9814 
1999        14545       5578 
2000        40526      16819 
2001        43135      16731 
2002        32600      14574 
2003        61432      25465 
2004        48181      18479 
2005        85909      26401 
2006       111344      35566 
2007       205172      62879 
2008       126278      35922 
2009       102790      28876 
2010       119345      33131 
2011       179148      49541 
2012       166373      46037 
2013       257472      73113 
2014       641372     163517 
2015       745070     197706 
2016       573449     153022 
2017       612033     164062 
2018       404692     113441 
2019       940817     229993 
2020       694895     178242 
2021       902136     216098 
2022       669635     191517 
2023       610772     175827 
2024       202420      58225