ng repeat key value

<!DOCTYPE html>
<html>

<head>
  <link data-require="bootstrap@3.3.5" data-semver="3.3.5" rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" />
  <link data-require="bootstrap@3.3.5" data-semver="3.3.5" rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootswatch/3.3.5/cosmo/bootstrap.min.css" />
  <link data-require="bootstrap@3.3.5" data-semver="3.3.5" rel="stylesheet" href="//maxcdn.bootstrapcdn.com/font-awesome/4.4.0/css/font-awesome.min.css" />

  <script data-require="jquery@1.11.3" data-semver="1.11.3" src="http://code.jquery.com/jquery-1.11.3.min.js"></script>
  <script data-require="bootstrap@3.3.5" data-semver="3.3.5" src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
  <script data-require="angular.js@1.4.7" data-semver="1.4.7" src="https://code.angularjs.org/1.4.7/angular.js"></script>

  <link rel="stylesheet" href="style.css" />
  <script src="script.js"></script>
</head>

<body ng-app='app'>
  <div ng-controller="listController">
    <div class="panel panel-info" ng-repeat="(key, prop) in technicians">
      <div class="panel-heading" ng-repeat="(key2, prop2) in prop">
        <h3 class="panel-title">{{key2}}</h3>
      </div>
      <div class="panel-body" ng-repeat="(key3, prop3) in prop">
        <div ng-repeat="vale in prop3">
          <a href="{{year.year.file}}" class="btn btn-default" ng-repeat="year in vale.value_1">{{year.year}}</a>
        </div>
      </div>
    </div>
  </div>
</body>

</html>

var app = angular.module("app", []);

app.controller("listController", ["$scope", "$http",
  function($scope, $http) {
    $http.get('employees.json')
      .then(function(res) {
        $scope.technicians = res.data["technicians"];
        $scope.inginiers = res.data["inginiers"];

      });
  }
]);

/* Styles go here */

{
    "technicians": [
    {
        "Tech 1": [
        {
            "value_1": [
            {
                "year": 2014,
                "file": "path_to_the_file"
            },
            {
                "year": 2015,
                "file": "path_to_the_file"
            }]
        },
        {
            "value_2": [
            {
                "year": 2014,
                "file": "path_to_the_file"
            },
            {
                "year": 2015,
                "file": "path_to_the_file"
            }]
        }]
    },
    {
        "Tech 2": [
        {
            "value_1": [
            {
                "year": 2014,
                "file": "path_to_the_file"
            },
            {
                "year": 2015,
                "file": "path_to_the_file"
            }]
        },
        {
            "value_2": [
            {
                "year": 2014,
                "file": "path_to_the_file"
            },
            {
                "year": 2015,
                "file": "path_to_the_file"
            }]
        }]
  }],
  "inginiersl": [
   {
      "Inginier 1": [
        {
            "value_1": [
            {
                "year": 2014,
                "file": "path_to_the_file"
            },
            {
                "year": 2015,
                "file": "path_to_the_file"
            }]
        },
        {
            "value_2": [
            {
                "year": 2014,
                "file": "path_to_the_file"
            },
            {
                "year": 2015,
                "file": "path_to_the_file"
            }]
        }]
   },
   {
      "Inginier 2": [
        {
            "value_1": [
            {
                "year": 2014,
                "file": "path_to_the_file"
            },
            {
                "year": 2015,
                "file": "path_to_the_file"
            }]
        },
        {
            "value_2": [
            {
                "year": 2014,
                "file": "path_to_the_file"
            },
            {
                "year": 2015,
                "file": "path_to_the_file"
            }]
        }]
  }]
}