@Test
public void testColumnPercents() throws Exception {

  Table bush = Table.read().csv("../data/bush.csv");
  bush.addColumns(bush.dateColumn("date").year());
  Table xtab = CrossTab.columnPercents(bush, "who", "date year");
  assertEquals(6, xtab.columnCount());
  assertEquals(1.0, xtab.doubleColumn(1).getDouble(xtab.rowCount() - 1), 0.00001);
}