Profitable Trade - Coca-Cola (KO) Puts

Today our KO puts expired worthless. The transaction was as follows:

Sold 2 KO Dec 17 2011 62.5 Puts@.71                  +130.47

We earned 1.04% in 26 days or 14.65% annual. If one were to calculate return on margin (ROM) our return with an initial margin requirement of 1794.99, comes to 7.26% or 102% annual.