Nearly all of the 20 largest law firms in Dallas are trying to improve the racial and ethnic diversity of their staffs — but few are succeeding, according to a survey released last week.

The Dallas Diversity Task Force, comprising the local bar associations for black, Hispanic and Asian-American attorneys, found that of the firms surveyed and rated on a scale of zero to 100, only two exceeded 70, the score at which the firm mirrors the demographics of the Texas Bar.