label: 'Year',  'Sales',    null, 'Expenses',     null
 role: domain,   data, certainty,     data,  certainty
       '2004',   1000,     false,      400,      true
       '2005',   1170,      true,      460,      true
       '2006',    660,      true,     1120,      false
       '2007',   1030,      true,      540,      false