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         1666        609 
1994         2326        839 
1995         3536       1228 
1996         3576       1256 
1997         2329        794 
1998        23260       9807 
1999        14526       5570 
2000        40476      16796 
2001        43054      16695 
2002        32496      14526 
2003        61252      25393 
2004        47991      18405 
2005        85450      26271 
2006       110920      35442 
2007       204167      62609 
2008       125344      35671 
2009       101966      28652 
2010       118451      32899 
2011       177718      49148 
2012       165097      45621 
2013       256113      72440 
2014       640034     162599 
2015       741702     196252 
2016       570339     152137 
2017       605350     162829 
2018       397759     111272 
2019       938979     229843 
2020       689045     176617 
2021       895874     214481 
2022       664988     190204 
2023       604264     173987 
2024       212817      61487