negotiate salary 求助

背景是：工作2年，准备在公司内部换工作，已经得到另外一个部门的offer, 跟现在工资一样。由于我们公司每个职位都标出最低工资，最高工资以及中间值。俺现在的工资水准属于20%的范围，negotiate 过一轮了，答应提高8%左右，也就是属于33%的范围，还没有达到50%的范围，俺觉得自己只有2年的工作经验，要想达到50%有点困难，但是如果能再negotiate提高到12%左右就比较满意了。

第一轮negotiate,俺提出的理由是：
1. Over two years work experience in quantitative analysis. Proficient in SAS, Microsoft Excel and Power Point. All of those skills are keys to success of this position.

2. Strong education background.**** (Talk about my degrees)

3. I have demostrated that I had the ability to make valuable contribution to my team. My 2008 anual review is **, which is well above the average. In my review, my manager wrote that "***“ (good words about me)。

4. Regarding my current salary, it is totally different situation. My current position is my first job in financial industry. After two years training and learning, I have developed the skills which are necessary to this industry.

收到HR的回信说 “in response to your email, we'd like to raise the offer from *** to ***. we believe this offer fairly reflects your education and experiece."

俺想进一步negotiate,可是感觉理由在上一封信里都说完了。基于HR的回信，请问我还能怎样negotiate呢？谢谢先！