Language independent value

I have a simple computed field: get a year from a datetime-field. I will use it as an argument for a summary-view (cck-date-fields don't work correct). My problem is that the computed field is stored three times in the database - for every language (de, en and und - don't know what the last one is). Now the counts in the summary view are three times higher as they should be.
Is there a way to store the field only one time?