Thanks, I was using the Census spreadsheet from their first link, and you were using the second link.
I still think that with the power and ease of a spreadsheet one ought to at least estimate the compounding effects. 
It matters for estimating seats in 2020, since adds more to the fast growing states.
A presumption of compounding might not be valid.
Even if fertility and mortality rates are constant, birth and death rates might not be, due to age distribution effects. Interstate migration to a state is dependent on migration from other states. As the population of Arizona, Nevada, and Idaho grow due to people moving from California, their growth rate may decline as the relative ratio of populations decreases.
There may also be seasonal factors in population growth. People with children may be more likely to move during the summer. The one year growth rate from July 1, 2010 to July 1, 2011 may be more reflective of trends than the 5-quarter growth rate that includes two 2nd quarters.
