Year	constant 2015 US$
2010	36109.25181313938
2011	36528.41135181062
2012	35938.40315111141
2013	34643.39733216477
2014	34157.81488678826
2015	32562.776868611232
2016	32269.260243494526
2017	31331.719105295615
2018	30469.76464986039
2019	30252.003725891525