A local bank makes automobile loans. It charges 4% per year in the following manner: if $3600 is borrowed to be repaid over a 3-year period, the bank interest charge is $3600 x 0.04 x 3 years = $432. The bank deducts the $432 of interest from the $3600 loan and gives the customer $3168 in cash. The customer must repay the loan by paying 1/36 of $3600, or $100, at the end of each month for 36 months. What nominal annual interest rate is the bank actually charging for this loan?