check password strength in c#

enum PasswordScore
        {
            Blank = 0,
            VeryWeak = 1,
            Weak = 2,
            Medium = 3,
            Strong = 4,
            VeryStrong = 5
        }

        private  PasswordScore CheckingPasswordStrength(string password)
        {
            int score = 1;
            if (password.Length < 1)
                return PasswordScore.Blank;
            if (password.Length < 4)
                return PasswordScore.VeryWeak;

            if (password.Length >= 8)
                score++;
            if (password.Length >= 12)
                score++;
            if (Regex.IsMatch(password, @"[0-9]+(\.[0-9][0-9]?)?", RegexOptions.ECMAScript))   //number only //"^\d+$" if you need to match more than one digit.
                score++;
            if (Regex.IsMatch(password, @"^(?=.*[a-z])(?=.*[A-Z]).+$", RegexOptions.ECMAScript)) //both, lower and upper case
                score++;
            if (Regex.IsMatch(password, @"[!,@,#,$,%,^,&,*,?,_,~,-,£,(,)]", RegexOptions.ECMAScript)) //^[A-Z]+$
                score++;
            return (PasswordScore)score;
        }