Import into a custom field of type YYYY

I am trying to import into a custom field Grad Year of type Date and format YYYY ( allowable values 25 years in past to 1 year from current date). See Grad Year : : Graduation on demo site
http://drupal.demo.civicrm.org/civicrm/admin/custom/group/field?reset=1&action=browse&gid=4

Example of data in custom field required - 2010

Imported CSV

Use Case:
Import Grad Year for multiple contacts using Import Contacts and using a CSV

Implementation:
Import Contacts does not have YYYY has an available import date format. (would be nice if YYYY was supported - wish I had the skills to work on it)

Hence changed the year in CSV to yyyy-mm-dd e.g. 2010-01-01 - CSV is as attached. (used contact id 144 for testing
http://drupal.demo.civicrm.org/civicrm/contact/view?reset=1&cid=144

Import successful - BUT the year in Grad Year:: Graduation is 1970 instead of 2010. No clue why. (again refer to test user on demo - http://drupal.demo.civicrm.org/civicrm/contact/view?reset=1&cid=144)