Wang Feng deposited 400 yuan of pocket money in the bank for a period of two years. After the maturity, he received an after-tax interest of 14.4 yuan. What is the annual interest rate of this deposit?
王风把400元零花钱存入银行，定期两年，到期后，他得到税后利息14.4元，这种存款的年利率是多少？
<gadget id="calculator">14.4 / 2 / 400</gadget>
<output>0.018</output>

<result>0.018</result>