a Many of the tables in this book include simple percentages or percentage distributions, for easy reading and ready comprehension. The reader will find that percentages in percentage distributions do not always add exactly to the total. That is because we have left off tenths of points and rounded the figures to whole numbers.

a Includes coal, petroleum and natural gas and primary electricity. Firewood, animal wastes and most other non-commercial fuels are excluded.

b Preliminary.

b Includes electricity, natural gas, fuel oil and gasoline; excludes energy from wood, coal, kerosene, or bottled gas. All 1972-73 figures are from national surveys conducted under the direction of the Washington Center for Metropolitan Studies. Whenever information is from sources other than the Center's research, references appear in notes at the end of each chapter. The Washington Center's surveys were in two parts. The first asked a series of almost 150 questions of a stratified sample of 1,455 households nationwide about their dwelling and habits affecting energy use, and their opinions about the energy situation. The second asked 125 utility companies serving the sample households how much electricity and natural gas the households used and how much they paid for them during the most recent 12 months. Details of the surveys are found in the Appendix.

c See Chapter Five for a discussion of indirect energy use.

a See Appendix Tables A2-1 and A2-4 for the annual period covered for use of electricity and natural gas. All tables showing household use of these fuels cover a 12-month period in 1972-73. See also footnote a to Table 5-1.

a Total refers to 1968, and total transportation is for 1970.

b Derived from 1972-73 data in Washington Center for Metropolitan Studies' Lifestyles and Energy Surveys which were applied to 1973 data from the U.S. Department of the Interior. See source below.

c Refers to air, rail, and taxi travel.

a Civilian labor force.

b Not available.