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         1280        477 
1994         1628        599 
1995         2894       1012 
1996         2895       1024 
1997         1784        618 
1998        21446       9125 
1999        12857       4955 
2000        37920      15659 
2001        39077      15150 
2002        34838      15098 
2003        56715      23589 
2004        45174      17359 
2005        79717      24564 
2006       102616      33005 
2007       186926      57980 
2008       105191      30250 
2009        88484      25006 
2010       140895      37897 
2011       149219      41449 
2012       140012      38858 
2013       213717      60953 
2014       542478     138056 
2015       795619     209425 
2016       638808     165377 
2017       541981     146739 
2018       335993      94495 
2019       848743     207366 
2020       587544     148941 
2021       798283     188732 
2022       605128     173233 
2023       545286     156046 
2024       602562     173141 
2025       558108     159375