Gallup conducted a poll from November 17 to 19, 2009, and the results showed that only 49% of the American people were satisfied with Obama's job. When he took office, his approval rate was 70%. How much less Americans support Obama? (The average population of the United States in the past five years is calculated as 271 million)
盖洛普民意调查所2009年11月17日至19日进行民意调查，调查结果显示，只有49%的美国民众满意奥巴马工作．他就职时的支持率是70%，支持奥巴马的美国人大约少了多少？(近五年美国人口均按2.71亿计算)
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">49 / 100</gadget>
<output>49/100 = around 0.49</output>

<gadget id="calculator">(7/10) - (49/100)</gadget>
<output>21/100 = around 0.21</output>

<gadget id="calculator">2.71 * (21/100)</gadget>
<output>0.5691</output>

<result>0.5691</result>