Modify the yAxis component from the previous example to set a difference of 1 between each tick:

yAxis: {
  title: {
    text: 'Revenue (in U.S. billion dollars)'
  },
  tickInterval: 1
}

We can also include HTML in our titles and other text properties by enabling the useHTML property. Let's point to the actual data source in our subtitle:

subtitle: {
  text: 'Source: <a href="http://www.npd.com" title="NPD Group">NPD Group</a>; AFJV',
  useHTML: true
}

Now, add a bit of CSS styling by using the style property:

style: {
  color: '#000000',
  textDecoration: 'underline'
}