Here is the supporting link. You can pick the time span at the top of the page. Why the hell don’t Santorum and Gingrich use this?
http://data.bls.gov/timeseries/LNS11300000
Because they are too busy attacking Romney or each other. What they fail to comprehend is that by making Obama and his criminal syndicate Administration the ONLY focus of their campaigns, they would attract voters away from Romney - and especially from disaffected conservatives on the sidelines - without ever mentioning Mitt's name.