A new Reserve Bank of Australia chart gives both banks and their critics new ammunition. The chart, published in the RBA's November Statement on Monetary Policy, released on Friday, shows that bank interest margins are far lower than their pre-2000 level, but also that they are still near their highest point in six years.The RBA's comments suggest it remains doubtful of banks' claims that they must raise variable mortgage rates by more than the amount of the RBA's cash rate increase. But it is also a reminder that margins remain far lower than they were a decade ago."In terms of net interest margins, banks have recently reported mixed results," the RBA said, in the November Statement. "Most have experienced a small decrease in margins, though some have experienced a small increase.""In aggregate, the net interest margin of the major banks has fluctuated in a relatively narrow range since 2004, between 2.25 and 2.5 percentage points."The Statement says that the process of rolling over maturing loans is raising bank funding costs. But, in recent months, a different force is pushing funding costs down: the falling spread between bank bills and the OIS (overnight indexed swap) rate."Overall, this suggests that, in aggregate, the major banks' funding costs are likely to have been little changed over recent months, though trends differ for individual banks depending on their mix of funding."The November Statement also notes that: * The five largest banks' share of home loan approvals has fallen to around six percentage points below its early-2009 peak, but remains well above pre-crisis levels.* Average rates on the major banks' term deposits "specials" remain around six per cent, having risen "considerably" more than the cash rate since early 2009.* The average interest rate on banks' outstanding variable-rate lending to large businesses has fallen by almost 10 basis points since the end of July, and is now 6.72 per cent.* Foreign currency bond issuance costs have been reduced by the fall in hedging costs represented by the drop in the cross-currency basis swap spread.* Kangaroo bond issuance reached A$10 billion in the September quarter, up from the June quarter's $6 billion. "So far this year, Kangaroo issuance has totalled A$35 billion, close to the previous annual record in 2006." The drop in the cross-currency basis swap spread is consistent with having more Kangaroo bond issuance relative to hedged foreign currency issuance.