You can also use this on the term list page with a change to use your table:

Create a hook_form_alter

  switch ($form_id) {
    case 'taxonomy_overview_terms':
      foreach ($form as $element_name => $element) {
        // Is it a term element?
        if (drupal_substr($element_name, 0, 4) == 'tid:') {
          $form[$element_name]['view']['#value'] .= ' ('. taxonomy_term_count_nodes($element['#term']['tid']) .')';
        }
      }
      break;     
  }

And you might want to explain it in hook_help

    case 'admin/content/taxonomy/%':
      return '<p>'. t('The numbers in parentheses are the published content counts tagged with that term.') .'</p>';