How do I calculate my productivity both as a developer and a tester?

I perform a dual role in our Scrum team - I am primarily a developer, but I also carry out testing part which forms the bulk of my contribution to the team. My actual work in the team consists of 30% development work and 70% testing work. Even though I was taken up in the team as a developer, I work mostly for QA section of the team. How should I calculate my productivity to the team? What metrics should be used?

Posted By - Jeremy