The Colts began their 2013 season at home, for the first time since 2009, against the Oakland Raiders.  The Raiders, who received the opening kickoff, would turn the ball over on a Terrelle Pryor interception by Colts cornerback Greg Toler.  The interception would allow Andrew Luck and the Colts offense to drive down the field and score the first touchdown of the season on a pass from Luck to Reggie Wayne.  Heading into the second quarter, the Colts defense would continue to prevent the Raiders from scoring, forcing Oakland to punt on second drive of the game.  Luck would again lead the Colts down the field in an eight play, 69 yard drive that would result in a touchdown pass from Luck to tight end Dwayne Allen, giving the Colts an early 14-0 lead.  Pryor and the Raiders would respond for the first time on their next offensive drive, which ended in a touchdown run from Darren McFadden.  Defensive stops by both the Colts and the Raiders would ensure no further scoring in the half and would allow Indianapolis to head into halftime with the 14-7 lead.  Indianapolis was forced to punt on their first offensive possession of the second half, while the Raiders would drive down to the Colts 20 yard line and would score on a Sebastian Janikowski field goal, cutting the Colts lead to 14-10 lead.  The Raiders would again begin to drive down the field and would score the go ahead touchdown early in the fourth quarter on a pass from Denarius Moore from Terrelle Pryor, giving the Raiders a 17-14 lead.  Andrew Luck, on the next Colts offensive drive, would lead the team down the field, 71 yards in 11 plays, with Luck himself scoring the game-winning touchdown on a 19-yard run.  Pryor and the Raiders would drive down to the Colts 24 yard line, though the drive would end with an interception by Antoine Bethea, sealing the Colts victory. With the win, the Colts went to 1-0 on the season and extended their home winning streak to seven games.
Question: How many years had past since the Colts had started a season at home?
Answer: 4