I am trying to draw a Google visualization pie chart based on below JSON. I am having issues since Google takes numerical data, instead of just plain objects. 

For example, I want a pie chart based on UseCase. Pie chart will list VDI,Upgrade,DEMO and show its proportion related to total. Please help.

Here is the JSON example
[{"Id":0,"ProcessedTime":"2012/01","Approver":"zoo","POC":"POC1","UseCase":"VDI"},{"Id":0,"ProcessedTime":"2012/02","Approver":"zoo","POC":"POC1","UseCase":"Upgrade"},{"Id":0,"ProcessedTime":"2012/03","Approver":"zoo","POC":"POC2","UseCase":"DEMO"},{"Id":0,"ProcessedTime":"2012/04","Approver":"victor","POC":"POC2","UseCase":"DEMO"},{"Id":0,"ProcessedTime":"2012/05","Approver":"victor","POC":"POC3","UseCase":"VDI"},{"Id":0,"ProcessedTime":"2012/06","Approver":"victor","POC":"POC3","UseCase":"Upgrade"},{"Id":0,"ProcessedTime":"2012/05","Approver":"tom","POC":"POC3","UseCase":"VDI"},{"Id":0,"ProcessedTime":"2012/06","Approver":"tom","POC":"POC3","UseCase":"Upgrade"}]

```
// Full source
google.setOnLoadCallback(drawChart);

function drawChart() {
    $.get('/Home/GetData', {},
function (data) {
var tdata = new google.visualization.DataTable();

tdata.addColumn('string', 'UseCase');
tdata.addColumn('int', 'Count');

// Reservation based on UseCase
var ReservationByUseCase = [];
for (var i = 0; i < data.length; i++) {
    var d = data[i];

    // If not part of array.. Add it
    if ($.inArray(d.UseCase, ReservationByUseCase) === -1)
    {
        var UseCaseValue = d.UseCase;
        var UseCaseCountValue = 1;
        ReservationByUseCase.push({ UseCase: UseCaseValue, UseCaseCount: UseCaseCountValue });
    }

    // If part of the array.. Increase count
    if ($.inArray(d.UseCase, ReservationByUseCase) !== -1) {
        var cUseCase = ReservationByUseCase[$.inArray(d.UseCase, ReservationByUseCase)];
        cUseCase.UseCaseCount = cUseCase.UseCaseCount + 1;

        ReservationByUseCase[$.inArray(d.UseCase, ReservationByUseCase)] = cUseCase
    }

}

for (var i = 0; i < ReservationByUseCase.length; i++) {
    tdata.addColumn(ReservationByUseCase[i].UseCaseValue, ReservationByUseCase[i].UseCaseCountValue)
    alert(ReservationByUseCase[i].UseCaseValue);
    alert(ReservationByUseCase[i].UseCaseCountValue);
}

var options = {
    title: "Reservations"
};

var chart = new google.visualization.PieChart(document.getElementById('chart_div'));
chart.draw(tdata, options);
});
}

```