To qualify as official development assistance $($ODA$),$ export credit must have a grant element of at least $25\%,$ calculated using a stated annual interest rate of $10\%.$ Suppose that the Export Development Corporation $($the agency of the Canadian government that provides export credit$)$ considers the following loan: $$100$ million, to be amortized over $6$ years by $12$ semi$-$annual payments, after a grace period of $4$ years during which only interest would be paid semi$-$annually. The stated annual interest rate is $6\%.$

Determine whether or not this loan would be qualified as ODA. What is the maximum interest rate the Corporation could charge for this loan to qualify as ODA?