Perhaps you should try some spelling variations:
"improving economic performance series." » "improve economic performance series.", "improved economic performance series.", "improving economic performance metrics.", "improving economic performance reviews.", "improving economic performance review."
"improving past performance risk." » "improving plant performance risk.", "improving port performance risk.", "improving based performance risk.", "improving past performance size.", "improving past performance based.", "improving past performance _.", "improving basic performance risk.", "improving asset performance risk.", "improving land 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 economic performance series.") or ("improving past performance risk."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving economic performance series.") OR ("improving past performance risk.")).
• Removing quotes may allow a broader search: (( improving economic performance series. ) or ( improving past performance risk. )).
• Adding a wildcard symbol may retrieve word variants: (("improving economic performance series.") or ("improving past performance risk."))*.