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. Author manuscript; available in PMC: 2016 Apr 1.
Published in final edited form as: Inj Prev. 2014 Feb 13;21(0):e23–e27. doi: 10.1136/injuryprev-2013-040999

Table 1.

Average annual miles driven by age, year, and graduated driver licensing exposurea

Age (yr) Year Graduated driver licensing exposureb No. of respondents with trip diaries Average annual miles driven Adjusted miles driven ratio (aMR) (95% CI)c
16 1995–1996 Absent 1,272 2,851
2001–2002 Absent 634 4,156
Present 1,289 2,907
2008–2009 Absent 130 2,332
Present 3,081 1,652
total 6,406 0.79 (0.63, 0.98)
17 1995–1996 Absent 1,145 6,018
2001–2002 Absent 615 6,128
Present 1,123 5,425
2008–2009 Absent 108 4,268
Present 3,007 3,711
total 5,998 0.80 (0.63, 1.03)
18 1995–1996 Absent 1,099 7,507
2001–2002 Absent 481 7,605
Present 883 6,923
2008–2009 Absent 98 5,656
Present 2,359 5,857
total 4,920 0.92 (0.77, 1.09)
20–24 1995–1996 Not applicable 4,314 10,727
2001–2002 Not applicable 5,638 10,827
2008–2009 Not applicable 6,519 9,222
total 16,471

Abbreviation: aMR: adjusted miles driven ratio: average annual miles driven exposed to graduated driver licensing (GDL) / average miles driven unexposed to GDL; CI: confidence interval; GDL: graduated driver licensing.

a

Data from the National Household Travel Survey.

b

Exposure to GDL means living in a state that has graduated driver licensing laws to restrict adolescent driving.

c

Adjusted miles driven ratios (aMR) compare the average miles driven by respondents exposed to GDL with those not exposed, adjusted for changes over time as well as changes among drivers 20–24 years.