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         3829       1326 
1996         3578       1257 
1997         2335        796 
1998        23277       9814 
1999        14551       5581 
2000        40545      16828 
2001        43153      16736 
2002        32620      14583 
2003        61489      25486 
2004        48223      18494 
2005        86003      26429 
2006       111439      35594 
2007       205409      62947 
2008       126404      35956 
2009       102956      28919 
2010       119556      33187 
2011       179433      49617 
2012       166665      46117 
2013       258050      73272 
2014       642151     163723 
2015       745897     197930 
2016       573642     153098 
2017       611563     163891 
2018       405165     113557 
2019       935219     228391 
2020       695956     178522 
2021       903471     216432 
2022       672198     192240 
2023       611588     176057 
2024       160618      45874