title: Can dc.js render a bar chart without dimension?
body: <p>I'd like to know if dc.js can render a bar chart without dimension, for example, a bar chart displaying the reduce result of ALL data.</p>
  
  <p><img src="https://i.stack.imgur.com/3eDPl.png" alt="enter image description here"></p>
  
  <p>When we want to render a bar chart we always do like this:</p>
  
  <pre><code>chart.width(400)
  .height(200)
  .dimension(...some Dimension here...)
  .group(...some Group here...)
  .valueAccessor(function (p) {
      return p.value.someValue;
  })
  .x(d3.time.scale().domain(["Global"]))
  .y(d3.scale.linear().domain([0, 100]))
  .yAxis().tickFormat(function (v) {
      return v + "%";
  }); 
  chart.render();
  </code></pre>
  
  <p>My question is what to put in the dimension and group in order to achieve my purpose? The documentation says that dimension() is mandatory.</p>
  
  <p>Thanks very much!</p>