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         4422       1526 
1996         3593       1262 
1997         2337        797 
1998        23319       9830 
1999        14590       5597 
2000        40643      16874 
2001        41657      16247 
2002        32787      14652 
2003        61720      25581 
2004        48499      18607 
2005        86598      26602 
2006       112110      35791 
2007       206713      63308 
2008       127608      36278 
2009       103874      29170 
2010       120560      33453 
2011       181539      50192 
2012       168576      46638 
2013       262265      74374 
2014       652837     166455 
2015       759589     201460 
2016       578915     154412 
2017       608391     162594 
2018       406868     114030 
2019       932245     227363 
2020       704977     180899 
2021       916466     220185 
2022       686176     196229 
2023       618548     178004 
2024       138437      39666