What is wrong with this calculation of how long Ken Jennings was the Jeopardy! champion?

Here is my rough estimate. He was champion for 74 consecutive shows. The show is on 5 days per week, so he was champion for 74/5 consecutive weeks, or about 15 weeks. 15 weeks is 7×15=105 days, about 3½ months.

According to this article (toward the bottom), he started his streak on June 2,2004 and won his last game on November 29,2004. That is about 6 months. Where did I go wrong?