Table:
text: Thailand Open (badminton)
Past winners
Past winners
Year_ Men_s_singles Women_s_singles Men_s_doubles Women_s_doubles Mixed_doubles
2003 Ronald Susilo Dai Yun Yoo Yong-sung Ha Tae-kwon Wei Yili Zhao Tingting Chen Qiqiu Zhao Tingting
2004 Boonsak Ponsana Yao Jie Luluk Hadiyanto Alvent Yulianto Zhang Dan Zhang Yawen Nathan Robertson Gail Emms
2005 Muhammad Hafiz Hashim Yao Jie Jung Jae-sung Lee Jae-jin Lee Kyung-won Lee Hyo-jung Lee Jae-jin Lee Hyo-jung
2006 Chen Yu Zhu Lin Lee Yong-dae Jung Jae-sung Lee Kyung-won Lee Hyo-jung Lee Yong-dae Hwang Yu-mi
2007 Chen Hong Zhu Lin Lee Jae-jin Hwang Ji-man Gao Ling Huang Sui He Hanbin Yu Yang
2008 Lin Dan Xie Xingfang Fu Haifeng Cai Yun Yang Wei Zhang Jiewen Xie Zhongbo Zhang Yawen

Question: What is the average year with Nathan Robertson Gail Emms in mixed doubles at the Thailand Open (Badminton)?