This poll was conducted entirely before the Iowa caucus.
Since it is a tracking poll over the course of a week or so, it takes several days for the full effect of recent events to be reflected.
Gallup has shown Santorum surging from 4% to 5% to 6% to 8% in their last four installments.
The latest shows Santorum at 8% on average over the past week, which likely means he was at 10-11% nationally on the day of the caucus.
Following his performance in Iowa his numbers will likely rise into the teens.