Tools for NSI data

• add_an_overlap — Add quarterly chained volumes series with annual overlap
• ann_overlap_2_baseprice — Calculates the price of previous year for chained price quarterly series
• ann_overlap_2_latsyvol — Calculates a volume at previous year prices series from nominal and chained volume quarterly series
• carryover — calculates the carry-over of a time series
• chained_laspeyres — Calculates Laspeyred chained indexes
• contrichution — Contribution to the growth rate of an agregate in chained prices
• lastyvol_2_ann_overlap — Calculates the price of previous year from nominal and volume at previous year prices series
• lastyvol_2_baseprice — Calculates previous year prices series from nominal and chained volume quarterly series