In Israel, the rate of interest is announced by the Bank of Israel at the end of every month. These announcements have been made since 1991, and provide the commercial banks with a benchmark for their rates on local-currency unindexed deposits and credit. This rate also affects the banks' prime rates. In the last few years prime interest has been about one and a half percentage points higher than the interest rate announced by the Bank of Israel. Prime rates are particularly important to mortgages linked to the prime interest rate. A mortgage linked to the prime interest rate based on the Bank of Israel rate is usually taken out for a period of up to 25 years.