While this is indeed a significant sum, this resulted in at most a 1% increase in investment, at a time when domestic investment was running at 15% of GNP. In other words, this does not explain growth rates several percentage points above their historic trend levels.
It should be noted, however, that growth may have been stimulated through other channels, for instance, by providing much-needed hard currency reserves which could be used for financing industrial raw materials. Over a third of Marshall aid was used in this way.