The health of a population's teeth can be measured by finding the average number of decayed, missing or filled teeth per person. This is called the DMFT. The graph shows the DMFT for four countries in the years between 1980 and 1995. Australia and the USA have fluoride added to their water but Japan and Belgium do not. The following statements were made. 1 The health of teeth has improved in all four countries. 2 Japan showed the greatest improvement. 3 Adding fluoride to the water causes the health of teeth to improve. Which statements are supported by the graph?

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