function outputGrid(i) {
  printf("%s\n", thisGrid)
  for(i=1; i<= col; i++)
     printf("%.1f%s", arr[i]/row, (i==col) ? RS : OFS)

  thisGrid=$0
  split("", arr)
  row=0
}

/^Grid/ {
  ( thisGrid != "") ? outputGrid() : thisGrid=$0
  next
}

/^[0-9][0-9]*/ {
  row++
  col=NF
  for(i=1; i <= NF; i++) {
    arr[i] += $i
  }
}
END {
  outputGrid()
}