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          509        192 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         3826       1325 
1996         3578       1257 
1997         2335        796 
1998        23277       9814 
1999        14551       5581 
2000        40545      16828 
2001        43151      16735 
2002        32620      14583 
2003        61485      25484 
2004        48223      18494 
2005        85983      26423 
2006       111429      35591 
2007       205383      62940 
2008       126398      35954 
2009       102936      28914 
2010       119523      33178 
2011       179384      49604 
2012       166657      46115 
2013       257992      73256 
2014       642055     163700 
2015       745804     197904 
2016       573554     153075 
2017       611826     163956 
2018       405072     113537 
2019       935452     228463 
2020       695828     178490 
2021       903260     216374 
2022       672062     192200 
2023       611512     176036 
2024       160529      45851