The "normal" level of lending rates may be lower now and in the years ahead than it has been over the past two decades, says the Reserve Bank of Australia.RBA deputy governor Philip Lowe made the statement last night in a speech at the Australian Business Economists' annual dinner. He argued that at least two factors could be keeping "normal" rates lower than they were in the past.The first was that Australia's post-GFC economic strength had pushed its dollar higher against the currencies of weaker economies. This meant interest rates (and, presumably, the official cash rate) were now being used "to offset some of the effects of an uncomfortably high exchange rate."The second was that, over the past two decades, first a credit boom and then a commodities boom had pushed up demand for funds and had, thus, inflated rates.In the years ahead, rates would still be affected by factors such as "the amount of spare capacity in the economy, the nature of capital flows and the rate of productivity growth," Lowe said."But it is possible that normal lending rates will be somewhat lower for a period owing to the combination of global factors and the legacy of the credit boom."