data.json

{
    "countries": [
      {
        "name": "Spain",
        "official-languages": 5,
        "ethnic-groups": [
          {
            "name": "Spainards",
            "percentage": 84.8
          },
          {
            "name": "Others",
            "percentage": 15.2
          }
        ],
        "cities":[
          {
           "name": "Madrid",
           "country": "Spain",
           "visited": false,
           "population":6713557,
           "would-visit-again": null
          },
          {
            "name": "San Sebastian",
            "country": "Spain",
            "visited": true,
            "population": 188102,
            "would-visit-again": true
          }
        ]
      },
      {
        "name": "Croatia",
        "official languages": 1,
        "ethinic groups": [
          {  "name": "Croats",
             "percentage": 90.42
          },
          {  "name": "Serbs",
             "percentage": 4.36
          },
          {  "name": "Others",
             "percentage": 5.22
          }
          
        ],
        "cities": [
          {
            "name": "Zagreb",
            "country": "Croatia",
            "visited": true,
            "population": 769944,
            "would-visit-again": false
          },
          {
            "name": "Split",
            "country": "croatia",
            "visited": true,
            "population": 161312,
            "would-visit-again": true
          }
        ]
      }
    ]
}