The graph shows the changes in mean blood lead levels in children under the age of 6 in Canada: • In 1972, the level was 19.0 micrograms per decilitre; • In 1984, the level was 12.0 micrograms per decilitre; • In 1988, the level was 6.0 micrograms per decilitre; • In 1991, the level was 3.2 micrograms per decilitre; • In 2010, the level was 1.35 micrograms per decilitre; • In 2015, the level was 0.67 micrograms per decilitre.