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         4275       1476 
1996         3587       1260 
1997         2334        796 
1998        23303       9824 
1999        14580       5593 
2000        40627      16866 
2001        41636      16238 
2002        32757      14640 
2003        61680      25563 
2004        48451      18588 
2005        86477      26568 
2006       111996      35758 
2007       206437      63232 
2008       127390      36220 
2009       103731      29129 
2010       120344      33394 
2011       181129      50080 
2012       168179      46530 
2013       261130      74068 
2014       647050     165050 
2015       752257     199657 
2016       577264     154079 
2017       610944     163355 
2018       407793     114262 
2019       932166     227316 
2020       700935     180014 
2021       929579     222512 
2022       678661     194125 
2023       617537     177741 
2024       148347      42540