Marriage is still a popular social practice in America, but divorce is becoming almost as "popular". Most Americans get married, but at the same time, fifty percent of their marriages end up in divorce. However, four out of five divorced people do not stay single. They get married for the second time to new partners. Sociologists tell us that in the 21st century, most American people will marry three or four times in one lifetime. Alvin Toffler, an American sociologist, culls this new social form social marriages. In his book Future Shock, Toffler gives many reasons for this change in American marriage. In modern society, people’s lives don’t stay the same for very long. Americans frequently change their jobs, their homes, and their circle of friends. So the person who was a good husband or wife ten years ago is sometimes not as good ten years later. After being married for some years, a husband or wife can feel that their lives have become very different, and they don’t have the same interests any more. Because of this, Toffler says, people in the 21st century will not plan to marry only one person for an entire lifetime. They will plan to stay married to one person for perhaps five or ten years, and then marry another. Most Americans will expect to have a "marriage career" that includes three or four marriages. The percentage of remarriage among divorced Americans is().