FIGURE 4.

Percentage of all deaths attributable to pneumonia and influenza (P&I), by surveillance week and year — 122 Cities Mortality Reporting System, United States, 2009–2014*

^* Data as of May 30, 2014.

^† The seasonal baseline proportion of P&I deaths is projected using a robust regression procedure, in which a periodic regression model is applied to the observed percentage of deaths from P&I reported by the 122 Cities Mortality Reporting System during the preceding 5 years.

^§ The epidemic threshold is set at 1.645 standard deviations above the seasonal baseline.