I have apache logs with size of each request and the time , I need to plot graph on amount of data transfered per unit time.

A sample document looks like below

```
{
    "@timestamp" : "2015-01-01T00:00:00",
    "bytes" : 20
}

```

For each minute , I want to take sum of the bytes field and plot that over a graph in Kibana 3. Can anybody help me on this?