ASP.NET Page size

I have a page with two gridviews to template item using HTML tables,  that refresh each 20 seconds that loads a realtime data from csv stream , when page is loaded the size is 30KB and it runs 24/7 , the admins reported that 30KB is consuming a lot of bandwidth over month and  the size should be optimized , I did all what I know to reduce white spaces, minimal use of control as I'm rendering data directly in cells,

<img src='<%# GetStationStatus(Convert.ToString(Eval("Date")), Convert.ToString(Eval("Time"))) %>' /><font class="RTUnit2"> <%# Eval("Time") %> </font></td><td style="background-color:azure;width:150px;text-align:right"><%# DataBinder.Eval(Container.DataItem, "Station") %></td>

I'm using following method to reload the page, the concern I have is to reduce  the size

$(document).ready(function pageCounter() {
    counter = 20;
    setInterval(function () {
        counter--;
        if (counter >= 0) {
            span = document.getElementById("counter");
            span.innerHTML = counter;
        }
        // Display 'counter' wherever you want to display it.
        if (counter === 0) {$("[id*=Button1]").click(); counter = 20;
        }
    }, 1000);
});

 what do I need to make the size of my page smaller

if any other information are needed please inform me

BR