Dreaded Belaeramie
1 year
Reversed it to show birth year, each bar is 100% of the cohort. More red, higher lead ug/DL as a % of the cohort.
Means that almost 50% of ppl born in 1970 have at least 20ug/DL of lead in their blood, but only 2-3% of ppl born in 1990 have that much.