Base on the knowledge of PHP, I has made a year dropdown list. Simply you need copy this code below and paste to your views page.
<?php $yearNow = date("Y");
    $yearFrom = $yearNow - 100;
    $arrYears = array();
    foreach (range($yearFrom, $yearNow) as $number) {
        $arrYears[$number] = $number;
    $arrYears = array_reverse($arrYears, true);
    echo $form->dropDownList($model,'dob',$arrYears,array('class'=>'form-control','prompt'=>'Year',));

This code will generate the range of year from now go back to 100 years.

  • date(“Y”) Get current year.
  • $yearFrom = $yearNow – 100 Range of year, input and change whatever you want.
  • range($yearFrom, $yearNow) Get year between current year and back to 100 years.
  • array_reverse($arrYears) reverse the year array, bring current year to the top.
  • $form->dropDownList() add year array to yii dropdown list.
If you want know more about dropdown list in yii or create a  dynamic dropdown list which can get data from database and update data using ajax, go here
Or create a drop down filter like this picture below, go here