Despite the popularity of Curious George, PBS's current cycle only produces 6 new episodes per season. To compare numbers, George's first season started with 40 episodes, then 20 in it's second season. PBS did state that this is part of their model, where shows start out with a high number of episodes and subsequent seasons receive smaller number.
"I think we all would like to see more production. It is a show we’re proud of, and the ratings have always been stellar."
"All that being said, it is critical for most of us in the voice acting business to have many shows, for one show does not a living make."