2017   (2597 top level nodes)
2016   (2822 top level nodes)
2015   (3824 top level nodes)
2014   (5022 top level nodes)
2013   (6814 top level nodes)
2012   (6837 top level nodes)
2011   (7055 top level nodes)
2010   (7015 top level nodes)
2009   (8799 top level nodes)
2008   (7989 top level nodes)
2007   (7900 top level nodes)
2006   (8984 top level nodes)
2005   (11882 top level nodes)
2004   (11452 top level nodes)
2003   (11887 top level nodes)
2002   (12533 top level nodes)
2001   (12642 top level nodes)
2000   (5981 top level nodes)
1999   (78 top level nodes)