You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Madonna_(entertainer)

Context:
Madonna embarked on the Confessions Tour in May 2006, which had a global audience of 1.2 million and grossed over $193.7 million, becoming the highest-grossing tour to that date for a female artist. Madonna used religious symbols, such as the crucifix and Crown of Thorns, in the performance of "Live to Tell". It caused the Russian Orthodox Church and the Federation of Jewish Communities of Russia to urge all their members to boycott her concert. At the same time, the International Federation of the Phonographic Industry (IFPI) announced officially that Madonna had sold over 200 million copies for her albums alone worldwide.

Question:
When did the Confessions Tour start?

May 2006