multiselect only submits one value

Hello,

I wanted to select and submit multiple values from a multiselect. But only one selected value gets submited .

Javascript

$(document).ready(function() {
$('.mdb-select').materialSelect();
});

html used

<div class="row">
  <div class="col-md-12">

    <select name="country" class="mdb-select colorful-select dropdown-primary md-form" multiple searchable="Search here..">
      <option value="" disabled selected>Choose your country</option>
      <option value="1">USA</option>
      <option value="2">Germany</option>
      <option value="3">France</option>
      <option value="4">Poland</option>
      <option value="5">Japan</option>
    </select>
    <label class="mdb-main-label">Label example</label>
    <button class="btn-save btn btn-primary btn-sm">Save</button>

  </div>
</div>

For example if I select Poland and Japan only the value japan will be submitted for the field country. So how do I get the values of each option ? Expected behaviour was to have 4 and 5 submitted as values for Poland and Japan.