Updating competency content by certain effective date

Summary

We use competencies in performence review and job profile. The content of competencies have changed for this year but we want to keep the old versions for last year's evalutions.

Content

We have not find a way to update competency content so that it wouldn't also replace the old content. Now it basically show the new content both in last year's and current year's performance evaluation when looking compentency description.

Any ideas how we can make this work? We have tried to give new effective date to competency but it didn't help.

Kind regards,

Juha