I suggest working this out step-by-step. You have a nice little table there. Try adding a measure to it: IF(Date > Today() - 7, 1, 0). Work out from there.
You may also want consider creating an extra field called DateNum, which would be Num(Date). This might make it easier to do comparisons.
Finally, in your load script, make sure that your DateFormat is 'YYYY-MM-DD'. It's not the default.