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        38883      16083 
2001        39657      15414 
2002        31081      13926 
2003        58277      24241 
2004        46797      17960 
2005        82249      25309 
2006       105965      33989 
2007       193699      59799 
2008       115486      32996 
2009        95163      26805 
2010       114339      31738 
2011       161880      44877 
2012       153201      42439 
2013       225902      64330 
2014       569079     145065 
2015       794267     208044 
2016       664773     172425 
2017       561052     151747 
2018       359150     100858 
2019       876502     214026 
2020       629532     160352 
2021       849253     202124 
2022       632661     181097 
2023       571067     163178 
2024       635718     183047 
2025       117329      33134