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          444        170 
1992          721        293 
1993         1283        478 
1994         1631        600 
1995         2903       1015 
1996         2895       1024 
1997         1790        620 
1998        21454       9129 
1999        12875       4962 
2000        38015      15701 
2001        39355      15257 
2002        32833      14431 
2003        56374      23499 
2004        45388      17439 
2005        79980      24646 
2006       102956      33109 
2007       187806      58217 
2008       106581      30625 
2009        89551      25284 
2010       141614      38086 
2011       150952      41922 
2012       141999      39396 
2013       215179      61362 
2014       547877     139476 
2015       795591     209363 
2016       646111     167767 
2017       544639     147415 
2018       338761      95249 
2019       851734     207944 
2020       593864     150694 
2021       804259     190343 
2022       608913     174303 
2023       548721     157034 
2024       608438     174579 
2025       526725     150397