%partprice = (
  1 => {
    '2005-01-01' => 1.99, # new year special.
    '2005-01-02' => 8.99, # back to normal.
    '2005-02-15' => 9.99, # price bump.
    '2005-04-01' => 9.49, # on sale.
    '2005-04-08' => 9.99, # sale's over.
  },
);