Parse usage/overall.

def _usage_overall(raw):
    '''
    Parse usage/overall.
    '''
    data = {}
    for line in raw.split("\n")[1:]:
        keyset = [item.strip() for item in re.sub(r"\s+", " ", line).split(":", 1) if item.strip()]
        if len(keyset) == 2:
            key = re.sub(r"[()]", "", keyset[0]).replace(" ", "_").lower()
            if key in ['free_estimated', 'global_reserve']:  # An extra field
                subk = keyset[1].split("(")
                data[key] = subk[0].strip()
                subk = subk[1].replace(")", "").split(": ")
                data["{0}_{1}".format(key, subk[0])] = subk[1]
            else:
                data[key] = keyset[1]

    return data