only year select datepicker

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datetimepicker/4.17.37/css/bootstrap-datetimepicker.css">
<script src="https://code.jquery.com/jquery-2.2.2.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.10.3/moment.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datetimepicker/4.17.37/js/bootstrap-datetimepicker.min.js"></script>
<div class="form-group">
   <div class='input-group date' >                                                
    <input type="text" id="dayPicker">
   </div>
   <div class='input-group date' >                                                
    <input type="text" id="monthPicker">
   </div>
   <div class='input-group date' >                                                
    <input type="text" id="yearPicker">
   </div>
</div>

JavaScript

$('#yearPicker').datetimepicker({
    format      :   "YYYY",
    viewMode    :   "years", 
});

$('#monthPicker').datetimepicker({
    format      :   "MM",
    viewMode    :   "months", 
});

$('#dayPicker').datetimepicker({
    format      :   "DD",
    viewMode    :   "days", 
});