Add 3 series:
US_elec - the total hourly demand and supply (generation) for electricity in the US since July 2015
US_source - the hourly demand for electricity in the US by energy source (natural gas, coal, solar, etc.) since July 2018
Cal_elec - The California subregion hourly demand by operator since July 2018
All series updated up to Dec 31 2019
NEWS.md file to track changes to the package.