Mr. Wang typed a manuscript, originally planned to finish typing in 25 minutes, but ended up completing the task in 20 minutes. By what percentage has Mr. Wang's work efficiency increased?
王老师打一份稿件，原计划25分钟打完，结果20分钟完成了任务．王老师的工作效率提高了百分之几？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / 25</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">(1/20) - (1/25)</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">(1/100) / (1/25)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>