 look like:    Subject   Date 0        0 Jan-00 0        0 Feb-00 0        0 Mar-00 0        0 Apr-00 0        0 May-00 0        0 Jun-00 0        0 Jul-00 0        0 Aug-00 0        0 Mar-00 00       0 Apr-00 00       0 May-00 00       0 Jun-00 00       0 Jul-00 00       0 Aug-00 00       0 Mar-00 00       0 Apr-00 00       0 May-00 00       0 Jun-00 00       0 Jul-00 00       0 Aug-00  structure(list(Subject = c(0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,  0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L), Date = structure(c(0L,  0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,  0L, 0L, 0L