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        14550       5580 
2000        40543      16827 
2001        43149      16734 
2002        32620      14583 
2003        61485      25484 
2004        48219      18493 
2005        85973      26420 
2006       111417      35588 
2007       205369      62936 
2008       126398      35954 
2009       102936      28914 
2010       119507      33175 
2011       179373      49601 
2012       166982      46128 
2013       257957      73246 
2014       641978     163680 
2015       745772     197896 
2016       573489     153057 
2017       612097     164042 
2018       405007     113521 
2019       936059     228610 
2020       695831     178488 
2021       903167     216344 
2022       671710     192095 
2023       611447     176016 
2024       160613      45865