22  Figure 4  Gross yields on BOTs and 10-year BTPs, average cost and average residual maturity of debt (per cent and year)  Source: Istat, for interest expenses. (1) Ratio between interest expense in the preceding 4 quarters and the stock of the debt at the end of the year-earlier quarter.
– (2) The yield at issue is the average, weighted by the issue amounts allotted, of the compound allotment rates at the auctions settled during the month. – (3) Average monthly yield at maturity of the benchmark traded on the online government securities market. – (4) Right-hand scale. 23  Designed by the Printing and Publishing Division of the Bank of Italy