题目内容：
Most couples who get married or decide to live together generally plan to have children. Several years ago, people thought that having big families was common and this was seen as an advantage. That was mainly because children began working at an early age to help provide for the family. But with the changing times and with the cost of living getting higher every single year, having a big family is no longer considered to be a practical option. In fact, more couples consider that they have only one child and some do not have any desire to become parents at all.According to the Australian Institute of Family Studies, by 1986, women aged 40 to 44 years, were considerably more likely to have given birth to two children than three children (36% vs. 27%) or four or more children (19%). However, taken together, women were still more likely to have had three or more children than to have had two children (46% vs. 36%).
In recent years, women were more likely to have had two children than three or more children – a trend that was most marked in the most recent period (38% vs. 25% in 1996; 38% vs. 22% in 2006). These days, most families in Australia have two children. But the number of women who had given birth to a single child increased progressively from only 8% in 1981 to 13% in 2006.
The U.S. Census Bureau states that there are approximately 14 million only children in Am
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