Ant & Dec are an English comedy TV presenting duo, consisting of Anthony McPartlin OBE  and Declan Donnelly OBE , from Newcastle upon Tyne, England. Formed after their meeting as actors on CBBC's drama, Byker Grove, the duo have led successful careers as television presenters, with hosting credits including SMTV Live, CD:UK, Friends Like These, Pop Idol, Ant & Dec's Saturday Night Takeaway, I'm a Celebrity...Get Me Out of Here!, PokerFace, Push the Button, Britain's Got Talent, Red or Black?, and Text Santa. Due to a difference in height - Ant being the taller at 5 ft 8 in , and Dec being two inches shorter at 5 ft 6 in  - the pair identify themselves in the media by adopting the use of the 180-degree rule, with the exception of some early publicity shots. In addition to presenting, the duo are accomplished actors - both had leading roles in the 2006 film Alien Autopsy - operate as television producers - they own their own production company, Mitre Television  - have presented the annual Brit Awards in 2001, 2015 and 2016, and are former pop musicians who operated under the aliases of their characters from Byker Grove. In a 2004 poll for the BBC, Ant & Dec were named the eighteenth most influential people in British culture.
Question: How many years do these events span for?
Answer: 15