The file P$03\_20.$xlsx contains monthly values of indexes that measure the amount of energy necessary to heat or cool buildings due to outside temperatures. $($See the explanation in the Source sheet of the file.$)$ These are reported for each state in the United States and also for several regions, as listed in the Locations sheet, from $1931$ to $2000.$ For each of the Heating Degree Days and Cooling Degree Days sheets, create a new Season variable with values "Winter," "Spring," "Summer," and "Fall."

Winter: $($Dec$,$ Jan, Feb$)$

Spring: $($Mar$,$ Apr, May$)$

Summer: $($Jun$,$ Jul, Aug$)$

Fall: $($Sep$,$ Oct, Nov$)$

a$.$ Find the mean, median, and standard deviation of Heating Degree Days $($HDD$),$ broken down by Season, for the $48$ contiguous states location $($code $5999).$