I got the idea from Calculated Risk to directly compare new with existing home sales. A huge "gap" exists between the two which was explained by CR as:
The initial gap was caused by the flood of distressed sales. This kept existing home sales elevated, and depressed new home sales since builders couldn't compete with the low prices of all the foreclosed properties.
The spike in existing home sales last year was due primarily to the first time homebuyer tax credit.
The first chart shows the "gap" (i.e. the huge collapse in new home sales vs. existing).