By how much does a high saving rate enhance a family’s future living standard?

The Spends and the Thrifts are similar families, except that the Spends save 5 percent of their income each year and the Thrifts save 20 percent. The two families began to save in 1995 and plan to continue to save until their respective breadwinners retire in the year 2030. Both families earn $40,000 a year in real terms in the labor market, and both put their savings in a mutual fund that has yielded a real return of 8 percent per year, a return they expect to continue into the future. Compare the amount that the two families consume in each year from 1995 to 2030, and compare the families’ wealth at retirement.