Overall domestic government spending on health doubled in low-income countries over 12 years to reach $18 billion in 2006. That is three times the amount of development assistance for health the governments received. However, in sub-Saharan Africa where many governments receive significant health aid directly, the aid appears to be in part replacing domestic health spending instead of fully supplementing it. Data on government health spending are often missing entire years of information and can be difficult to reconcile.