Public investment, which can be used as a proxy for infrastructure investment, in developed countries was at a historic low at 3.4 per cent of GDP in 2015, against 4.7 in 1980 and about 6 per cent in the 1960s. In emeiging economies, it fell from above 8 per cent of GDP in the early 1980s to 4.3 per cent in 2000, recovering to 5.7 per cent in 2008 and declining again thereafter (figure 4.10). The decline in public investment in developing countries in the 1980s and 1990s can be linked to adoption of fiscal adjustment policies in response to the debt crises and as part of structural adjustment programmes. The world as a whole is, therefore, underinvesting, and consequently creating a cumulative infrastructure gap, even though uncertainty remains as to its exact order of magnitude.