The followingchartis the years of life expected at birth, as estimated by the National Center for Health Statistics.

Year	All	Male	Female
1900	47.3	46.3	48.3
1910	50.0	48.4	51.8
1920	54.1	53.6	54.6
1930	59.7	58.1	61.6
1940	62.9	60.8	65.2
1950	68.2	65.6	71.1
1960	69.7	66.6	73.1
1970	70.8	67.1	74.7
1980	73.7	70.0	77.5
1990	75.4	71.8	78.8

1. Using information from http://www.cdc.gov/nchs/data/hus/2013/018.pdf, justify the accuracy of the model.