The phenomenon is usually attributed to the lower relative salaries compared to other professions, as well as to cultural factors (OECD 2005, 2009, 2012a). In Kazakhstan the gender imbalance is particularly apparent with more than eight women out of every 10 teachers in primary and secondary education on average (81%). Kazakhstan has a larger share of its teachers aged 30 years or younger (24% in 2011) than in OECD countries on average, and a smaller proportion of teachers aged 50 years or older (21% in 2011, see Table 4.1). Nonetheless, these numbers indicate that nearly one-quarter of the teacher population is at or nearing the age of retirement and that significant efforts will need to be made to ensure that this does not result in important teacher shortages, especially in light of the expected increase in the student population (National Centre for Educational Quality Assessment - NCEQA, 2011).