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         2326        839 
1995         3735       1294 
1996         3578       1257 
1997         2335        796 
1998        23274       9813 
1999        14535       5574 
2000        40499      16806 
2001        43092      16711 
2002        32555      14553 
2003        61337      25427 
2004        48063      18435 
2005        85663      26334 
2006       111090      35491 
2007       204727      62762 
2008       125830      35801 
2009       102397      28770 
2010       118949      33027 
2011       178506      49365 
2012       165903      45854 
2013       256555      72757 
2014       641832     163163 
2015       745243     197080 
2016       573144     152828 
2017       610815     163747 
2018       402651     112709 
2019       942798     230843 
2020       692206     177496 
2021       899217     215344 
2022       667764     191007 
2023       607073     174781 
2024       198939      57216