function ParticipantsCountries()
 {
     $chart = new gvGeoChart();
     $chart->setTitle("Participants countries")->setDataHeader("Country", "Participants")->setSize(800, 400)->opt('is3D', true);
     $country_names = Localization::get_country_names();
     foreach (model_datasource('system')->ExecuteSql("SELECT country, count(*) as cnt FROM participants GROUP BY country ORDER BY cnt DESC") as $row) {
         $chart->addDataRow($country_names[$row['country']], intval($row['cnt']));
     }
     return $chart;
 }