1. A computer system comprising: a data storage device for receiving, storing, and providing access to historical claim data; a computer processor for executing program instructions and for retrieving the historical claim data from the data storage device; a memory, coupled to the computer processor, for storing program instructions for execution by the computer processor; a categorical aggregation component comprising program instructions stored in the memory for providing categorized and aggregated historical claim data by identifying medical claim categories based on the historical claim data, each of the one or more claim categories associated with a respective set of claim characteristics, identifying claims of the historical claim data associated with one of the claim categories, assigning each identified claim to one of a plurality of total severity ranges based on the total severity of the identified claim, and determining an average cost per claim year divided amongst a plurality of expense categories for claims of each total severity range when executed by the computer processor; and a communication device, coupled to the computer processor, to output categorized and aggregated historical claim data including the average cost per claim year for claims of each total severity range.