Season 1 PBS , 2003 Season 2 PBS , 2005 Season 3 PBS Season 4 PBS , 2007 Season 5 PBS , 2008 Season 6 PBS , 2009 Season 7 PBS , 2010 Season 8 PBS , 2011 Season 9 PBS , 2012 Season 10 PBS , 2013 Season 11 PBS , 2014 - 2015 Season 12 PBS , 2015 Season 17 PBS , 2020 - 2021