onst drilldownData = [{
                dataGroupId: 'animals',
                data: [
                    ['Cats', 4],
                    ['Dogs', 2],
                    ['Cows', 1],
                    ['Sheep', 2],
                    ['Pigs', 1]
                ]
            }, {
                dataGroupId: 'fruits',
                data: [
                    ['Apples', 4],
                    ['Oranges', 2]
                ]
            }, {
                dataGroupId: 'cars',
                dat