The Nanjing Consumer Association conducted a survey on the labeling of the baby bottles on the market. The scale of the capacity of a certain baby bottle is 20 ml, but the actual capacity is only 15.3 ml. How many percent is the error rate of the labeling of the capacity of this feeding bottle?
南京市消费者协会对市场上的奶瓶的容里标注进行调查，某种奶瓶的容量标注的刻度为20毫升，而实际容量只有15.3毫升．这种奶瓶的容量标注的误差率达到了百分之几？
<gadget id="calculator">20 - 15.3</gadget>
<output>4.7</output>

<gadget id="calculator">4.7 / 20</gadget>
<output>0.235</output>

<result>0.235</result>