function switch_chart(vis_chart) {
document.getElementById("2week_graph").style.display = "none";
document.getElementById("4week_graph").style.display = "none";
document.getElementById("8week_graph").style.display = "none";
document.getElementById("12week_graph").style.display = "none";
document.getElementById("alltime_graph").style.display = "none";

switch(vis_chart)
{
case 2:
  document.getElementById("2week_graph").style.display = "";
  break;
case 4:
  document.getElementById("4week_graph").style.display = "";
  break;
case 8:
  document.getElementById("8week_graph").style.display = "";
  break;
case 12:
  document.getElementById("12week_graph").style.display = "";
  break;
case 99:
  document.getElementById("alltime_graph").style.display = "";
  break;
}
}