Number of Indigenous Australians in prisons more than doubles, despite drop in crime rates- Incarceration rates have more than doubled among Australia's Indigenous population.In a keynote speech to the Australian Institute of Criminology's annual conference on Monday, federal MP Andrew Leigh will attribute the rise to tougher bail laws and longer sentences.The figure is even higher in states such as WA, where 3.5 per cent of Indigenous adults are behind bars.Figures estimate that for every prisoner, there are an average of 1.8 children with an incarcerated parent."The factors that have driven the fall in crime include better community policing, immigration, rising incomes, the removal of lead from petrol and the mandatory installation of electronic immobilisers on new vehicles," he will say."