This histogram shows the trend for CCGI metric. In this graph the main ranges can be identified:
When CCGI is low the Internal Class Implementation (ICI) is too high with respect to the external class complexity and, therefore the class cannot be used like a black box.
CCGI around 0.6 is considered optimal and the class has an optimal ratio between ECD and CC.
When CCGI is equal to 1 means that ECD=CC and, therefore the ICI is quite 0. This situation depicts class defined, but not implemented yet or C structure.