Google's data only goes back to 2004, which postdates most of Anne Rice's Lestat novels. Vampire popularity appears to have declined steadily from 2004 through 2007. In 2008 the rush to create vampire entertainment was in full effect, with Twilight and HBO's True Blood driving people online to search for more information. It appears to be in decline in 2009.
I did another graph, looking at the relevance and interplay between twilight, true blood, and vampires. The results are surprising. (click for larger graph)
The graph suggests that the vampire resurgence (which is waning) is probably driven by interest in Twilight.