Wyoming Oil issued $100 million in perpetual debt (at par) with an annual coupon of 7%. Wyoming will pay interest only on this debt. Wyoming's corporate tax rate is expected to be 21% for the foreseeable future. Assume that five years have passed since Wyoming issued this debt. While tax rates have remained at 21%, interest rates have dropped so that Wyoming's current cost of debt capital is now only 4%. Wyoming's annual interest tax shield is now closest to $______ million.

Group of answer choices 4.20 1.47 40 60