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         4290       1481 
1996         3590       1261 
1997         2334        796 
1998        23306       9825 
1999        14580       5593 
2000        40629      16867 
2001        41639      16239 
2002        32757      14640 
2003        61685      25565 
2004        48456      18590 
2005        86499      26575 
2006       112001      35760 
2007       206464      63239 
2008       127409      36225 
2009       103752      29135 
2010       120366      33400 
2011       181164      50090 
2012       168216      46540 
2013       261236      74097 
2014       647125     165071 
2015       752368     199686 
2016       577246     154076 
2017       610441     163259 
2018       407815     114272 
2019       932090     227290 
2020       701009     180034 
2021       929724     222557 
2022       678809     194166 
2023       617608     177762 
2024       147792      42430