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          468        178 
1992          740        300 
1993         1296        483 
1994         1664        611 
1995         3000       1048 
1996         2959       1046 
1997         1822        631 
1998        21599       9190 
1999        13201       5076 
2000        38478      15907 
2001        39290      15262 
2002        32231      14271 
2003        57540      23951 
2004        46163      17720 
2005        80944      24933 
2006       104479      33558 
2007       191042      59086 
2008       111560      31962 
2009        92396      26057 
2010       144662      38876 
2011       156595      43459 
2012       147972      41021 
2013       219611      62594 
2014       563959     143738 
2015       798181     210126 
2016       656779     170704 
2017       553515     149838 
2018       350172      98389 
2019       861804     210399 
2020       615247     156584 
2021       827684     196493 
2022       619141     177145 
2023       558638     159538 
2024       614565     176974 
2025       224622      64193