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         3799       1316 
1996         3578       1257 
1997         2335        796 
1998        23277       9814 
1999        14545       5578 
2000        40526      16819 
2001        43128      16728 
2002        32594      14571 
2003        61429      25464 
2004        48163      18473 
2005        85891      26396 
2006       111315      35558 
2007       205140      62870 
2008       126242      35912 
2009       102733      28860 
2010       119288      33116 
2011       179108      49530 
2012       166297      46016 
2013       257345      73077 
2014       641206     163470 
2015       744868     197654 
2016       573364     152997 
2017       611486     163972 
2018       404577     113407 
2019       941394     230229 
2020       694677     178185 
2021       901932     216038 
2022       669560     191496 
2023       610403     175688 
2024       201093      57865