_id	year	PM_expo	reference
1	1990	29.5	screencapture-databank-worldbank-org_25.01.2-21.pdf
2	2000	30	screencapture-databank-worldbank-org_25.01.2-21.pdf
3	2011	30.9	screencapture-databank-worldbank-org_25.01.2-21.pdf
4	2012	31.3	screencapture-databank-worldbank-org_25.01.2-21.pdf
5	2013	30.3	screencapture-databank-worldbank-org_25.01.2-21.pdf
6	2014	28.6	screencapture-databank-worldbank-org_25.01.2-21.pdf
7	2015	26.8	screencapture-databank-worldbank-org_25.01.2-21.pdf
8	2016	25.2	screencapture-databank-worldbank-org_25.01.2-21.pdf
9	2017	25.6	screencapture-databank-worldbank-org_25.01.2-21.pdf