function hideItem(){
  var i, obj, tbls;

  tbls = document.getElementsByTagName("table");
  for (i = 0; i < tbls.length; i++){
    obj = tbls[i];
    if (obj.id.substring(0,5) == "mnth_"){
      obj.style.display = "none";
    }
  }
  return false;
}

function clickItem(id){
  var objmnth, objicon;

  objmnth = document.getElementById("mnth_" + id);
  objicon = document.getElementById("icon_" + id);
  if (objmnth.style.display == "none"){
    objmnth.style.display = "block";
    objicon.innerHTML = "▲";
  } else {
    objmnth.style.display = "none";
    objicon.innerHTML = "▼";
  }
  return false;
}