Perhaps you should try some spelling variations:
"improving poor performance series." » "improving poor performance metrics.", "improving poor performance reviews.", "improving poor performance review.", "improving export performance series.", "improving sector performance series.", "improving _ performance series.", "improving power performance series.", "improving food performance series.", "improving indoor performance series."
"improving co performance evidence." » "improving do performance evidence.", "improving crop performance evidence.", "improving job performance evidence.", "improving _ performance evidence.", "improving macro performance evidence.", "improving food performance evidence."

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"improving co performance evidence.\") OR (\"improving poor performance series.\"))~".
• Removing quotes may allow a broader search: (( improving co performance evidence. ) OR ( improving poor performance series. ))~.
• Adding a wildcard symbol may retrieve word variants: (("improving co performance evidence.") OR ("improving poor performance series."))*.