Retrieve metrics of interest from globals table.

def _parse_qualimap_globals(table):
    """Retrieve metrics of interest from globals table.
    """
    out = {}
    want = {"Mapped reads": _parse_num_pct,
            "Duplication rate": lambda k, v: {k: v}}
    for row in table.find_all("tr"):
        col, val = [x.text for x in row.find_all("td")]
        if col in want:
            out.update(want[col](col, val))
    return out