Since 937, by the decision of the Emperor Taizu of Song, the palace examination was supervised by the emperor himself. In 992, the practice of anonymous submission of papers during the palace examination was introduced; it was spread to the departmental examinations in 1007, and to the prefectural level in 1032. From 1037 on, it was forbidden for examiners to supervise examinations in their home prefecture. Examiners and high officials were also forbidden from contacting each other prior to the exams. The practice of recopying papers in order to prevent revealing the candidate's calligraphy was introduced at the capital and departmental level in 1015, and in the prefectures in 1037. Statistics indicate that the Song imperial government degree-awards eventually more than doubled the highest annual averages of those awarded during the Tang dynasty, with 200 or more per year on average being common, and at times reaching a per annum figure of almost 240.