Given the speed of the spoken language, one hour of simultaneous interpretation amounts to approximately 9,000 words. In about 2 hours, therefore, an interpreter will have processed and uttered roughly 20,000 words. It is interesting to compare this figure of 20,000 words with the amount handled in written translation. As we saw, earlier, the UN lays down a standard of between 6 and 8 pages, or 2,000 to 3,000 words per day. The daily contractual work load for conference translator is calculated on the basis of 2,000 words for ordinary texts and 1,000 words for technical texts. Thus, in one day, the interpreter processes 10 times as many words as the translator. However, as these words are concentrated into the time the interpreter is actually speaking (1/3 of the meeting time), the interpreter is in fact working 30 times faster than a translator. Whatever the fundamental differences between translation and interpretation, it is obvious that a working speed 3,000 % greater than that of a translator cannot be sustained for long, which is why simultaneous interpreters relieve one another every 20 minutes or half an hour.