Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           14          7 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          216         77 
1991          861        308 
1992          675        277 
1993         1222        458 
1994         1581        587 
1995         2705        950 
1996         2799        991 
1997         2768        943 
1998        24380       8705 
1999        13172       5020 
2000        37188      15302 
2001        42211      16600 
2002        35760      15304 
2003        58420      23901 
2004        45956      17495 
2005       308482     138781 
2006       335143     149454 
2007       194923      60244 
2008       111794      31819 
2009        92477      25821 
2010       140749      37462 
2011       149609      40675 
2012       177128      38768 
2013       233528      58945 
2014       530506     130301 
2015       755303     196796 
2016       626642     161725 
2017       525182     142800 
2018       313056      88484 
2019       821253     201265 
2020       543122     137720 
2021       736629     172651 
2022       570657     163575 
2023       521791     149449 
2024       565806     162591 
2025       547311     155076 
2026       249087      53212