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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4050       1400 
1996         3581       1258 
1997         2331        795 
1998        23291       9819 
1999        14561       5585 
2000        40575      16842 
2001        41566      16209 
2002        32666      14603 
2003        61589      25525 
2004        48331      18539 
2005        86190      26486 
2006       111631      35650 
2007       205769      63048 
2008       126750      36050 
2009       103278      29009 
2010       119815      33252 
2011       180057      49787 
2012       167144      46250 
2013       259123      73565 
2014       644528     164387 
2015       748964     198775 
2016       575282     153542 
2017       612772     163934 
2018       406361     113873 
2019       933228     227701 
2020       696825     178898 
2021      1025661     241588 
2022       674711     193012 
2023       613480     176612 
2024       157106      44983