It needs also to be borne in mind that while the returns to lower-secondary education have declined over time, those to post-secondary education have risen (Lemieux, 2006, Machado and Mata, 2001), an indication that the demand for skills has outpaced its supply, which is possibly associated with skill-biased technological change. Empirical evidence suggests that any negative effects of tuition fees on participation rates can be fully offset through improvements in the financial support for students (OECD, 2008c, Heller, 1999). For a discussion on the practical implementation of income-contingent loans and student financial support schemes see OECD (2008c).