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Each year the CPI-U-RS is updated to include the past year’s data and the effect of any changes or new adjustments to previous research series data. A new adjustment was introduced this year; in 2016 the index for prescription drugs was switched from a geometric means formula to a Laspeyres formula. This year’s research series incorporates the effect of that change from 2010 through 2015. The data and related materials are available at the CPI-U Research Series page.