function display_tbl(){
var isnone = document.getElementById("tbl_1").style.display;
if ( isnone == "none" ){
document.getElementById("tbl_1").style.display="block";
}
else{
document.getElementById("tbl_1").style.display="none";
}
}


function display_tb2(){
var isnone = document.getElementById("tbl_2").style.display;
if ( isnone == "none" ){
document.getElementById("tbl_2").style.display="block";
}
else{
document.getElementById("tbl_2").style.display="none";
}
}