How to calculate Cumulative Frequency?

@import url(‘https://fonts.googleapis.com/css?family=Droid+Serif|Raleway’);

.axis–y .domain {
display: none;
}

h1 {
color: black;
text-align: center;
margin-top: 15px;
margin-bottom: 0px;
font-family: ‘Raleway’, sans-serif;
}

h2 {
color: black;
font-size: 20px;
text-align: center;
margin-bottom: 15px;
margin-top: 15px;
font-family: ‘Raleway’, sans-serif;
}

p {
color: black;
text-align: center;
margin-bottom: 15px;
margin-top: 15px;
font-family: ‘Raleway’, sans-serif;
}

#words_intro {
color: black;
font-family: Raleway;
max-width: 550px;
margin: 25px auto;
line-height: 1.75;
}

#words_outro {
color: black;
font-family: Raleway;
max-width: 550px;
margin: 25px auto;
line-height: 1.75;
}

#words {
color: black;
font-family: Raleway;
max-width: 550px;
margin: 25px auto;
line-height: 1.75;
padding-left: 100px;
}

#calcTitle {
text-align: center;
font-size: 20px;
margin-bottom: 0px;
font-family: ‘Raleway’, serif;
}

#hr_top {
width: 30%;
margin-bottom: 0px;
margin-top: 10px;
border: none;
height: 2px;
color: black;
background-color: black;
}

#hr_bottom {
width: 30%;
margin-top: 15px;
border: none;
height: 2px;
color: black;
background-color: black;
}

.input_label_calc {
display: inline-block;
vertical-align: baseline;
width: 350px;
}

#button_calc {
border: 1px solid;
border-radius: 10px;
margin-top: 20px;
padding: 10px 10px;
cursor: pointer;
outline: none;
background-color: white;
color: black;
font-family: ‘Work Sans’, sans-serif;
border: 1px solid grey;
/* Green */
}

#button_calc:hover {
background-color: #f6f6f6;
border: 1px solid black;
}

.label_radio {
text-align: center;
}

#words_table {
color: black;
font-family: Raleway;
max-width: 350px;
margin: 25px auto;
line-height: 1.75;
}

function calc() {

//remove current table if one exists
var element = document.getElementsByTagName(‘table’)[0];
if(element) {element.parentNode.removeChild(element)}

//get input values
var input_data = document.getElementById(‘input_data’).value.split(‘,’).map(Number);

//calculate stuff
var occurrence = function (array) {
“use strict”;
var result = {};
if (array instanceof Array) { // Check if input is array.
array.forEach(function (v, i) {
if (!result[v]) { // Initial object property creation.
result[v] = [i]; // Create an array for that property.
} else { // Same occurrences found.
result[v].push(i); // Fill the array.
}
});
}
return result;
};
var size = Object.keys(occurrence(input_data)).length;

//create array of relative and cumulative values
var relFreqArray = [];
for (var i = 0; i < size; i++){
relFreqArray[i] = (occurrence(input_data)[Object.keys(occurrence(input_data))[i]].length)
}

for (var cumsum = [relFreqArray[0]], i = 0, l = relFreqArray.length-1; i<l; i++) {
cumsum[i+1] = cumsum[i] + relFreqArray[i+1];
}

//generate table of frequencies
var table = document.createElement('table');
function boldHTML(text) {
var element = document.createElement("b");
element.innerHTML = text;
return element;
}
var tr = document.createElement('tr');

var td1 = document.createElement('td');
var td2 = document.createElement('td');
var td4 = document.createElement('td');

td1.appendChild(boldHTML('Value'));
td2.appendChild(boldHTML('Frequency'));
td4.appendChild(boldHTML('Cumulative Frequency'));

tr.appendChild(td1);
tr.appendChild(td2);
tr.appendChild(td4);

table.appendChild(tr);
for (var i = 0; i < size; i++){
var tr = document.createElement('tr');

var td1 = document.createElement('td');
var td2 = document.createElement('td');
var td4 = document.createElement('td');

var text1 = document.createTextNode(Object.keys(occurrence(input_data))[i]);
var text2 = document.createTextNode(occurrence(input_data)[Object.keys(occurrence(input_data))[i]].length);
var text4 = document.createTextNode(cumsum[i]);

td1.appendChild(text1);
td2.appendChild(text2);
td4.appendChild(text4);

tr.appendChild(td1);
tr.appendChild(td2);
tr.appendChild(td4);

table.appendChild(tr);
}
document.getElementById('table_output').appendChild(table);

//output results
//document.getElementById('ss').innerHTML = ss.toFixed(2);
}