Perhaps you should try some spelling variations:
"improving sector performance metrics." » "improving sector performance measures.", "improve sector performance metrics.", "improving eco performance metrics.", "improving sewer performance metrics."
"borrowing country performance series." » "borrowing country performance studies.", "borrowing country performance size.", "borrowing countries performance series.", "borrowing costs performance series.", "borrowing cost performance series."

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• Performing a fuzzy search may retrieve terms with similar spellings: (("borrowing country performance series.") or ("improving sector performance metrics."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("borrowing country performance series.") OR ("improving sector performance metrics.")).
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