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        13174       5067 
2000        38473      15905 
2001        39288      15261 
2002        32219      14266 
2003        57528      23946 
2004        46161      17719 
2005        80935      24930 
2006       104465      33554 
2007       191012      59078 
2008       111512      31949 
2009        92359      26047 
2010       144643      38871 
2011       156538      43444 
2012       147921      41006 
2013       219567      62582 
2014       563711     143675 
2015       797870     210060 
2016       656633     170666 
2017       553385     149801 
2018       350055      98357 
2019       861570     210342 
2020       615014     156518 
2021       827370     196452 
2022       618628     177044 
2023       557935     159454 
2024       614166     176925 
2025       225350      64418