Passage: Michael, who came out as gay in 1998, was an active LGBT rights campaigner and HIV/AIDS charity fundraiser. Michael's personal life and legal troubles made headlines during the late 1990s and 2000s, as he was arrested for public lewdness in 1998 and was arrested for multiple drug-related offenses after that time. The 2005 documentary A Different Story covered his career and personal life. Michael's first tour since 1991, the 25 Live tour, spanned three tours over the course of three years; 2006, 2007, and 2008. Six years later, he performed his final concert at London's Earls Court in 2012. In the early hours of 25 December 2016, Michael was found dead at his home in Goring-on-Thames, Oxfordshire aged 53. A coroner's report attributed his death to natural causes.

Question: In what years did Michael's 25 Live tour take place?
2006, 2007, and 2008