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         3562       1236 
1996         3576       1256 
1997         2329        794 
1998        23263       9808 
1999        14526       5570 
2000        40476      16796 
2001        43059      16697 
2002        32496      14526 
2003        61254      25394 
2004        47991      18405 
2005        85478      26279 
2006       110920      35442 
2007       204215      62622 
2008       125356      35674 
2009       102006      28664 
2010       118477      32906 
2011       177777      49164 
2012       165231      45643 
2013       256297      72474 
2014       639289     162548 
2015       742312     196359 
2016       570557     152186 
2017       605886     162910 
2018       399599     111556 
2019       939300     229932 
2020       689319     176695 
2021       896236     214567 
2022       665108     190238 
2023       604370     174017 
2024       213673      61698