trail2.vl

{
    "mark": {
        "type": "trail",
        "order": false
    },
    "data": {
        "url": "https://vega.github.io/vega-lite/data/driving.json"
    },
    "$schema": "https://vega.github.io/schema/vega-lite/v3.json",
    "encoding": {
        "size": {
            "field": "year",
            "type": "temporal",
            "legend": null
        },
        "x": {
            "field": "miles",
            "scale": {
                "zero": false
            },
            "type": "quantitative"
        },
        "y": {
            "field": "gas",
            "scale": {
                "zero": false
            },
            "type": "quantitative"
        }
    }
}