function display_speak(year, _this)
{
    var lnk = document.getElementById('speak_' + year);
    
    lnk.className = lnk.className == 'hidden_speak' ? 'visibility_speak' : 'hidden_speak';
    
    _this.className = _this.className == 'speak_active' ? 'speak_normal' : 'speak_active';
    
    return false;
}