The average home price going up more than 80% from 2000 to 2006 is extreme. The average home price going up 100% from 2000 to 2018 isn't that crazy. Maybe prices will go down, maybe not, I wouldn't call it a bubble yet. There are also a higher percentage of people living in cities, and I would suspect more people renting, which can drive purchase prices up for legitimate reasons.
That index is not adjusted for inflation.