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         3940       1363 
1996         3578       1257 
1997         2331        795 
1998        23285       9817 
1999        14561       5585 
2000        40565      16837 
2001        45776      17612 
2002        32654      14598 
2003        61578      25520 
2004        48321      18535 
2005        86165      26479 
2006       111598      35641 
2007       205684      63024 
2008       126647      36022 
2009       103198      28986 
2010       119782      33243 
2011       179865      49736 
2012       167049      46225 
2013       258820      73489 
2014       644242     164308 
2015       748462     198646 
2016       575021     153486 
2017       613104     164069 
2018       406034     113785 
2019       934406     228034 
2020       696957     178955 
2021       905370     217049 
2022       674018     192811 
2023       612880     176434 
2024       160609      45804