Why do I have 300k jobs in a day but my history graph shows 30k per day?

On my dashboard it shows around 30,000 per day while I have 300,000 completed jobs from the last 24 hours.

What is the history graph on the dashboard counting? I can go to the last page on my completed jobs list and see that all 300k completed jobs really are all from the last day so purging is working right.

Edit: I think the weekly history graph might be off by a factor of 10;i.e. showing 29k for 290k jobs.