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         3005       1062 
1997         1925        664 
1998        22341       9441 
1999        13620       5227 
2000        38908      16095 
2001        39665      15419 
2002        31103      13936 
2003        58295      24249 
2004        46828      17971 
2005        82295      25322 
2006       106005      34001 
2007       193838      59837 
2008       115634      33036 
2009        95249      26829 
2010       109892      30660 
2011       162108      44939 
2012       153410      42496 
2013       226111      64391 
2014       569230     145109 
2015       792729     207633 
2016       664804     172457 
2017       561406     151849 
2018       359565     100973 
2019       877082     214183 
2020       630188     160527 
2021       850051     202347 
2022       633144     181235 
2023       571975     163433 
2024       636010     183129 
2025       107243      30273