Hi @thecorkboard
Please save the date data as yymmdd. This is the default and most effective format.
To then retrieve only the year data, you can do this:
$date = get_field('date');
// $date = 19881123 (23/11/1988)
// extract Y,M,D
$y = substr($date, 0, 4);
source: http://www.advancedcustomfields.com/resources/field-types/date-picker/