The format is:
List of 3
$ airbagAvail : num [1:13, 1:2, 1:4] 1068 1120 1089 1033 940 ...
..- attr(*, "dimnames")=List of 3
.. ..$ years : chr [1:13] "1998" "1999" "2000" "2001" ...
.. ..$ D_airbagAvail: chr [1:2] "no" "yes"
.. ..$ injury : chr [1:4] "P_injury" "D_injury" "tot" "prop"
$ airbagDeploy: num [1:13, 1:2, 1:4] 1133 1226 1196 1151 1091 ...
..- attr(*, "dimnames")=List of 3
.. ..$ years : chr [1:13] "1998" "1999" "2000" "2001" ...
.. ..$ D_airbagAvail: chr [1:2] "no" "yes"
.. ..$ injury : chr [1:4] "P_injury" "D_injury" "tot" "prop"
$ restraint : num [1:13, 1:2, 1:4] 780 783 735 714 741 645 634 561 558 494 ...
..- attr(*, "dimnames")=List of 3
.. ..$ years : chr [1:13] "1998" "1999" "2000" "2001" ...
.. ..$ D_airbagAvail: chr [1:2] "no" "yes"
.. ..$ injury : chr [1:4] "P_injury" "D_injury" "tot" "prop"