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         3985       1378 
1996         3581       1258 
1997         2331        795 
1998        23285       9817 
1999        14561       5585 
2000        40567      16838 
2001        41966      16342 
2002        32656      14599 
2003        61583      25522 
2004        48321      18535 
2005        86180      26483 
2006       111627      35649 
2007       205719      63035 
2008       126732      36045 
2009       103239      28998 
2010       119804      33249 
2011       179958      49761 
2012       167515      46259 
2013       259056      73546 
2014       644458     164368 
2015       748874     198750 
2016       575357     153561 
2017       613873     164181 
2018       406203     113832 
2019       934439     228043 
2020       696777     178886 
2021       905467     217078 
2022       674270     192885 
2023       613411     176573 
2024       161732      46131