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         3862       1337 
1996         3578       1257 
1997         2331        795 
1998        23280       9815 
1999        14551       5581 
2000        40545      16828 
2001        45814      17623 
2002        32627      14586 
2003        61499      25490 
2004        48238      18501 
2005        86029      26437 
2006       111462      35601 
2007       205494      62970 
2008       126466      35972 
2009       103017      28935 
2010       119642      33207 
2011       179535      49645 
2012       166786      46151 
2013       258292      73341 
2014       642404     163797 
2015       746223     198019 
2016       573971     153195 
2017       611469     163844 
2018       405507     113636 
2019       934548     228164 
2020       697189     179015 
2021       904746     216878 
2022       673108     192552 
2023       611765     176127 
2024       159633      45584