your attention. chart 1 : average contribution to real per capita gdp growth growth rates, in % source : ecb computation on world bank, wdi database. chart 2 : trends in youth population percentage of population aged 14 years and below source : world bank. chart 3 : trends in working age population percentage of population aged between 15 and 64 source : world bank. chart 4 : developments in r & d expenditure public expenditure on r & d as % of gdp source : world bank. note : for italy and brazil the latest available data point is 2006. chart 5 : human capital and economic growth sources : barro - lee ( 2010 ) ; world bank, wdi database. chart 6 : growing wage premium to high skilled labour and wage differential in the us sources : goldin and katz ( 2007 ). note : “ college graduate wage premium ” is based on the college / high school wage differential ( in logs ). “ high school graduate wage premium ” is based on the high school / eighth grade wage differential ( in logs ). chart 7 : relative earnings from employment, by level of educational attainment for 25 - 64 year - olds, 2007 source : oecd. note : upper secondary and post - secondary non - tertiary education = 100. data for italy refer to 2006 ( latest available year ) chart 8 : level of education source : oecd. chart 9 : public spending on education total public spending on education as % of government expenditure source : world bank. chart 10 : full - time graduate students in science and engineering in the us ( i ) source : national science foundation. chart 11 : full - time graduate students in science and engineering in the us ( ii ) % of total graduates source : national science foundation. chart 12 : countries of origin of non - us citizens earning phds at us colleges and universities % of total doctorates awarded source : national opinion research center at the university of chicago.

non - financial corporations are, by and large, based on shorter - duration interest rates, even in countries in which the rate fixation period for bank credit is generally longer. as regards setting mortgage interest rates, the picture is more dispersed, with short and medium 3 / 5 bis central bankers'speeches maturities being the relevant benchmark in some euro area countries, and long - term interest rates in others. from this perspective, the complementary nature of our instruments – with forward guidance anchoring the short - to - medium term segment of the curve, and the asset purchase programme acting on the long - term segment – has given our monetary policy strategy an extra edge over the last few years. it has made it more targeted and thus more impactful. * * * as the economic prospects brighten, higher expected returns on business investment will make borrowing conditions increasingly attractive. this, in and of itself, will reinforce accommodation and make sure that inflation sustainably converges towards our objective of below, but close to, 2 % over the medium term. but our mission is not yet accomplished. we need patience and persistence. we need to be patient, because inflation convergence needs more time to show through convincingly in the data. the euro area ’ s economic environment is improving, and the fat negative tail to inflation expectations, which was so visible at the start of our asset purchase programme, has virtually disappeared ( see chart 4 ). this strengthens our confidence that headline inflation will gradually move towards the governing council ’ s objective. but measured inflation remains exceedingly volatile and metrics of underlying price pressures continue to be subdued. the entire distribution of inflation expectations still needs to shift a fair distance to the right. 4 / 5 bis central bankers'speeches and we need to be persistent, because the baseline scenario for future inflation remains crucially contingent on very easy financing conditions which, to a large extent, depend on the current accommodative monetary policy stance. 5 / 5 bis central bankers'speeches