The graph shows a city's daily rate of use of electricity (in millions of kilowatts). Estimate the total daily usage of electricity by using rectangles whose height is given by the value of the function at the left side of each rectangle. Let the width of each rectangle be 2 hours. The estimate of the city's total daily usage of electricity for the given day is million kilowatt-hours. (Round to the nearest whole number as needed.) 14+ 12- 10- 8 6 4 2 Millions of kilowatts Midnight 4 AM BAM Noon 4 PM 8PM. Midnight