headers

<table>
    <thead>
        <tr>
            <th rowspan="2">Mes</th>
            <th colspan="2" id="p1">España</th>
            <th colspan="2" id="p2">Francia</th>
        </tr>
        <tr>
            <th id="h1">Hablan español</th>
            <th id="h2">No hablan español</th>
            ...
        </tr>
    </thead>
    <tbody>
        <tr>
            <th id="m1">Enero</th>
            <td headers="p1 h1 m1">10</td>
            ...
        </tr>
    </tbody>
</table>