To construct the following graphs, I averaged real GDP growth, quarter to quarter from 1947:Q2 to 2006:Q1 separately by quarter. Thus, in the following graph, the bars show the average growth rate (annualized) for the first quarter, second quarter, and so on. I was surprised to see that growth typically declines during the year:
A plot of the average pattern since 1947 against the four most recent quarters shows the pattern is not atypical, but it is exaggerated:
Note: Most recent are 2005:Q2=3.3%, 2005:Q3=4.1%, 2005:Q4=1.6%, 2006:Q1=4.7%, the average values are in the previous graph.
Average real GDP growth over the last four quarters is 3.41%. The average growth rate over all quarters since 1947:2 is 3.36%. Thus, the average growth rate over the last four quarters is average.