function showStockHistory() {
    document.getElementById('displayhistory').style.display = "none";
    document.getElementById('hidehistory').style.display = "block";
    document.getElementById('historygraph').style.display = "block";
}

function hideStockHistory() {
    document.getElementById('displayhistory').style.display = "block";
    document.getElementById('hidehistory').style.display = "none";
    document.getElementById('historygraph').style.display = "none";
}