function displayPeriodImage(divID,timevar)
{if(document.getElementById("oneweek_div"+timevar)!=null)
{document.getElementById("oneweek_div"+timevar).style.display="none";}
if(document.getElementById("threeweeks_div"+timevar)!=null)
{document.getElementById("threeweeks_div"+timevar).style.display="none";}
if(document.getElementById("sixweeks_div"+timevar)!=null)
{document.getElementById("sixweeks_div"+timevar).style.display="none";}
if(divID)
{if(document.getElementById(divID)!=null)
{document.getElementById(divID).style.display="block";}}}