Discrepancy in San Francisco population?

I'm comparing Google public data (http://bit.ly/1ibkhwL) vs. acf tabulated data.

Specifically, I'm looking at a big jump that appears between 2007 and 2008 in ACF data:
factfinder2.census.gov/.../0500000US06075
factfinder2.census.gov/.../0500000US06075

There's a jump from 764,976 to 808,976 that appears in ACF data, but not on Google data (799,185 to 808,001). From 2008 on, the data is very close, but not 2007 and below.

I'm trying to use the ACF PUMS data to break down SF demographics, and I'm stuck here trying to understand where this discrepancy came from.

FWIW, the numbers on the bay area census site agree with Google (www.bayareacensus.ca.gov/.../SanFranciscoCounty.htm)