Which of these table designs is better for performance?
A billion records a year isn't much. 

With partitioning (per Costtype maybe) and archiving it is manageable.

The number of data items to store is still 200k * 13 * N. As columns, you'll get less rows per page and it will take more space than as rows. You may gain if "CostType1" is not a fixed length datatype, but it's marginal.

"KISS" as they say