Magento - Get list of all Manufacturers with product count

$attribute = Mage::getModel('eav/entity_attribute')->loadByCode('catalog_product', 'manufacturer');

$valuesCollection = Mage::getResourceModel('eav/entity_attribute_option_collection')
            ->setAttributeFilter($attribute->getData('attribute_id'))
            ->setStoreFilter(0, false);

$preparedManufacturers = array();           
foreach($valuesCollection as $value) {
    $preparedManufacturers[$value->getOptionId()] = $value->getValue();
}  

if (count($preparedManufacturers)) {
    echo "<h2>Manufacturers</h2><ul>";
    foreach($preparedManufacturers as $optionId => $value) {
        echo "<li>" . $value . " - (" . $optionId . ")</li>";
    }
    echo "</ul>";
}

What I am looking for is a way to display the number of products
associated with each of the manufacturers. Can someone please tell me
the way of doing this?

Many thanks