Cloudwatch Dashboard for Appsync which shows 500 Errors as Percentage of Total Requests

dashboard.json

{
    "metrics": [
        [ { "expression": "(m2/m1)*100", "label": "percentage", "id": "e1", "yAxis": "right" } ],
        [ "AWS/AppSync", "5XXError", "GraphQLAPIId", "XXXXX", { "label": "5xx errors", "id": "m2" } ],
        [ "...", { "stat": "SampleCount", "label": "total requests", "id": "m1" } ]
    ],
    "region": "ap-southeast-2",
    "title": "500 Errors as Percentage of Total Requests",
    "stat": "Sum",
    "yAxis": {
        "left": {
            "label": "Count",
            "showUnits": false
        },
        "right": {
            "min": 0,
            "max": 100
        }
    },
    "view": "timeSeries",
    "stacked": false,
    "annotations": {
        "horizontal": [
            {
                "label": "goal",
                "value": 1
            }
        ]
    }
}