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        32224      14268 
2003        57537      23950 
2004        46163      17720 
2005        80941      24932 
2006       104468      33555 
2007       191023      59081 
2008       111526      31953 
2009        92371      26050 
2010       144651      38873 
2011       156570      43452 
2012       147931      41009 
2013       219589      62588 
2014       563728     143681 
2015       797899     210065 
2016       656679     170678 
2017       553427     149813 
2018       350104      98370 
2019       861707     210373 
2020       615117     156548 
2021       827426     196468 
2022       618971     177106 
2023       558390     159502 
2024       614480     176958 
2025       225055      64327