A 2003 UC Berkeley report estimated that about five exabytes of new information were produced in 2002, and that 92% of this data was stored on hard disk drives. This was about twice the data produced in 2000. The amount of data transmitted over telecommunication systems in 2002 was nearly 18 exabytes—three and a half times more than was recorded on non-volatile storage. Telephone calls constituted 98% of the telecommunicated information in 2002. The researchers' highest estimate for the growth rate of newly stored information (uncompressed) was more than 30% per year.