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         2326        839 
1995         3790       1313 
1996         3578       1257 
1997         2335        796 
1998        23274       9813 
1999        14542       5577 
2000        40512      16812 
2001        43113      16721 
2002        32584      14567 
2003        61387      25447 
2004        48116      18456 
2005        85772      26363 
2006       111197      35522 
2007       204986      62830 
2008       126042      35857 
2009       102565      28815 
2010       119135      33076 
2011       178856      49460 
2012       166008      45935 
2013       256880      72912 
2014       641562     163342 
2015       745381     197415 
2016       573465     153039 
2017       611235     163904 
2018       404283     113324 
2019       942086     230557 
2020       693588     177882 
2021       900667     215733 
2022       668617     191238 
2023       609129     175361 
2024       199856      57491