(see Figure 1 in text)
| Mean | SE | |
|---|---|---|
| One person | 1.01 | 0.010 |
| Two people | 1.98 | 0.011 |
| Three people | 2.31 | 0.023 |
| Four people | 2.39 | 0.023 |
| Five people | 2.48 | 0.040 |
| Six people | 2.50 | 0.074 |
| Seven or more people | 2.76 | 0.113 |
NOTE: SE = standard error.
SOURCE: The 2001 National Household Travel Survey, household file, U.S. Department of Transportation.