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          471        179 
1992          749        303 
1993         1310        488 
1994         1692        621 
1995         3111       1085 
1996         3002       1061 
1997         1925        664 
1998        22341       9441 
1999        13620       5227 
2000        38906      16094 
2001        39665      15419 
2002        31089      13930 
2003        58288      24246 
2004        46822      17969 
2005        82281      25318 
2006       105992      33997 
2007       193818      59831 
2008       115583      33022 
2009        95227      26823 
2010       109851      30650 
2011       162016      44914 
2012       153350      42480 
2013       226052      64376 
2014       569153     145089 
2015       793449     207826 
2016       664782     172442 
2017       561262     151808 
2018       359432     100936 
2019       876906     214135 
2020       629940     160460 
2021       849815     202280 
2022       632961     181183 
2023       571697     163354 
2024       635880     183093 
2025       110901      30980