2018, PBS, 15 episodes

2017, PBS, 16 episodes

2016, PBS, 13 episodes

2015, PBS, 14 episodes

2014, PBS, 15 episodes

2013, PBS, 15 episodes

2012, PBS, 14 episodes

2011, PBS, 15 episodes

2010, PBS, 14 episodes

2009, PBS, 14 episodes

2008, PBS, 14 episodes

2007, PBS, 14 episodes

2006, PBS, 13 episodes

2005, PBS, 12 episodes

2004, PBS, 13 episodes

2003, PBS, 13 episodes

2002, PBS, 12 episodes

2001, PBS, 11 episodes

2000, PBS, 10 episodes

1999, PBS, 10 episodes

1998, PBS, 11 episodes

1997, PBS, 10 episodes

1996, PBS, 13 episodes

1995, PBS, 10 episodes

1994, PBS, 10 episodes

1993, PBS, 11 episodes

1992, PBS, 11 episodes

1991, PBS, 12 episodes

1990, PBS, 12 episodes

1989, PBS, 10 episodes

1988, PBS, 10 episodes