format
The format is:
mts [1:92, 1:4] 174 174 174 174 174 ...
- attr(*, "dimnames")=List of 2
..$ : NULL
..$ : chr [1:4] "Erie" "michHuron" "Ontario" "StClair"
- attr(*, "tsp")= num [1:3] 1918 2009 1
- attr(*, "class")= chr [1:2] "mts" "ts"source
http://www.lre.usace.army.mil/greatlakes/hh/greatlakeswaterlevels/historicdata/