Addws the following 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.