format
The format is:
num [1:51, 1:7, 1:13] 2 0 16 0 75 1 5 0 5 5 ...
- attr(*, "dimnames")=List of 3
..$ : chr [1:51] "1" "2" "3" "4" ...
..$ : chr [1:7] "injury" "age" "airbag" "restraint" ...
..$ : chr [1:13] "1998" "1999" "2000" "2001" ...source
http://www-fars.nhtsa.dot.gov/Main/index.aspx