Year current US$ 2007 33424896 2008 17935627 2009 10402350 2010 19545650 2011 18990187 2012 19714197 2013 21595662 2014 18015811 2015 17999515 2016 21706889 2017 24238350 2018 33883932 2019 37391324 2020 36290169 2021 36063879 2022 43398343