Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
2004 World Series
Table title:
Broadcasting
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Game </th><th colspan=1 rowspan=1 > Rating </th><th colspan=1 rowspan=1 > Share </th><th colspan=1 rowspan=1 > Audience (in millions) </th></tr>
<tr> <th colspan=1 rowspan=1 > 1 </th><td colspan=1 rowspan=1 > 13.7 </td><td colspan=1 rowspan=1 > 25 </td><td colspan=1 rowspan=1 > 23.17 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2 </th><td colspan=1 rowspan=1 > 15.9 </td><td colspan=1 rowspan=1 > 24 </td><td colspan=1 rowspan=1 > 25.46 </td></tr>
<tr> <th colspan=1 rowspan=1 > 3 </th><td colspan=1 rowspan=1 > 15.7 </td><td colspan=1 rowspan=1 > 24 </td><td colspan=1 rowspan=1 > 24.42 </td></tr>
<tr> <th class="highlighted"  colspan=1 rowspan=1 > 4 </th><td class="highlighted"  colspan=1 rowspan=1 > 18.2 </td><td colspan=1 rowspan=1 > 28 </td><td colspan=1 rowspan=1 > 28.84 </td></tr>
<tr> <th class="highlighted"  colspan=1 rowspan=1 > Average </th><td class="highlighted"  colspan=1 rowspan=1 > 15.8 </td><td colspan=1 rowspan=1 > 25.25 </td><td colspan=1 rowspan=1 > 25.47 </td></tr>
</table>
Question:
What was the broadcast rating of Game 4, and how did it affect the overall ratings of the 2004 World Series?
Answer:
Game 4 posted an 18.2 rating, giving the 2004 World Series an average of 15.8.