Perhaps you should try some spelling variations:
"improving food performance series." » "improving food performance metrics.", "improving food performance reviews.", "improving food performance review.", "improving good performance series.", "improving poor performance series.", "improving fund performance series.", "improving land performance series."
"improving rural performance risk." » "improving pupil performance risk.", "improving thermal performance risk.", "improving overall performance risk.", "improving rural performance size.", "improving rural performance based.", "improving rural performance _.", "improving urban performance risk.", "improving social performance risk."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving food performance series.") or ("improving rural performance risk."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving food performance series.") OR ("improving rural performance risk."))*.
• Removing quotes may allow a broader search: (( improving food performance series. ) or ( improving rural performance risk. ))*.