I've just started using XSLT and am trying to figure this out. Your help would be greatly appreciated.

Example XML file

<purchases>
    <item id = "1" customer_id = "5">
    </item>
    <item id = "2" customer_id = "5">
    </item>
    <item id = "7" customer_id = "4">
    </item>
</purchases>

Desired HTML Output:

<table>
    <tr><th>Customer ID</th><th>Number of Items Purchased</th></tr>
    <tr><td>5</td><td>2</td></tr>
    <tr><td>4</td><td>1</td></tr>
</table>

Customer with id number 5 has bought 2 items. Customer with id number 4 has bought 1 item.