and commission income. noteworthy among these fees is the relative increase in fees for selling products such as investment funds, against a backdrop of growing demand for these assets, bolstered by households seeking more profitable investments than deposits given their low returns. these developments have resulted in the ratio of gross income to assets, which includes fees in addition to net interest income, having fallen to a lesser extent than the net interest margin. banks have also made huge efforts to reduce their operating expenses through branch closures and job cuts, but to date these expenses have declined more moderately than gross income. this was reflected in a continued increase in the ratio between these two magnitudes, that is, the efficiency ratio, until 2017, which underlines the deterioration in their efficiency during this period. this trend seemed to come to a halt in 2018 when this ratio improved slightly. in terms of assets, in 2018 operating expenses were at similar levels to their pre - crisis ones. however, in a setting where the share of credit in assets is currently significantly lower than it was then, these expenses should also be smaller given that the costs associated with the management of non - credit assets are lower. the information in the consolidated statements also shows that the most recent levels of the efficiency ratio are above pre - crisis ones, therefore indicating a situation of lower efficiency. however, despite this deterioration, the ratios of the spanish banking system in this area continue to be more favourable than those of the main european banking systems and also than those of banks in the united states and japan, although they are worse than those of the scandinavian countries. main challenges affecting the future profitability of spanish banks next, i shall briefly mention the main challenges facing spanish banks which affect their future profitability outlook. these challenges are not confined to the spanish banking system but are largely shared with other jurisdictions. one of the major challenges which banks must face is linked to technological change. new technologies represent both threats and opportunities for banks. on one hand, they promote the emergence of new competitors, such as fintechs and big techs. the latter pose see ampudia and van den heuvel ( 2018 ). recent literature on monetary surprises distinguishes between purely monetary surprises and other surprises which disclose private information about the future state of the economy. see, for example, jaroncinski and karadi ( 2018 ). 11 / 13 a more obvious disruption, given their larger size and advantages in terms of the availability of information, a key asset in the digital and financial

2008 ) and poterba ( 1994 ). bis central bankers ’ speeches plays an important role. it has been empirically demonstrated that a higher degree of independence goes hand in hand with lower inflation rates. 8 to retain its independence, the central bank must show good performance, and acquire credibility and respect. this is the only way to make politicians and the public acknowledge the value of independence. tension during a crisis the financial and economic crisis provided an impressive demonstration of how important it is for fiscal and monetary policy to remain focused on their mandate and on sustainability. if public finances are already running a high level of indebtedness in good times, fiscal policy ’ s room for manoeuvre will be severely curtailed ( or very quickly used up ) in a crisis. in this situation, the central bank faces growing pressure from both politicians and the public to stimulate the economy with monetary policy measures. 9 if the central bank gives in to this pressure, it endangers its own independence and thereby its credibility. with an unsustainable fiscal policy, a stable monetary policy is no longer possible over the long term, even if the central bank is independent and not under pressure to stabilise the economy. a glance at economic history shows that high inflation rates have very often been accompanied by high levels of public debt. 10 monetary policy can only act in a crisis if its credibility is intact. some central banks, including the snb, have reached the zero lower bound for interest rates as a result of the recent crisis. even after hitting the lower bound, these central banks are still able to pursue their objectives. in order to retain their freedom of action, they are resorting to unconventional measures. some of these measures, such as purchasing securities of private sector issuers, are described as quasi - fiscal, meaning that they are part of monetary policy but, like fiscal policy, they have distribution effects. for this reason, they attract public and political attention and can therefore threaten the central bank ’ s independence. there is also a danger that politicians, economic agents and the public will expect monetary policy to have a solution for every problem. numerous problems in the real economy, such as the lack of competitiveness and the current account imbalances, are structural in origin. in this area, it is the responsibility of governments to introduce reforms. resolving such problems is outside the scope of monetary policy. the management of the recent financial and economic crisis has resulted in a much greater overlap between fiscal and monetary