The American College of Rheumatology says fibromyalgia may affect two to four percent of the population.

VOA: special.2011.07.26

It dropped dramatically in the period from 1954-- this is these filled black bars refer to this axis, polio cases per 100,000 population dropped down to only three or four cases by 1956.

患病率在一九五四年后的,一段时间里急剧下降,该坐标轴上的这些黑色柱形图表明,到一九五六年,小儿麻痹症的发病率,已经降低至每十万人中仅三到四人发病

耶鲁公开课 - 生物医学工程探索课程节选

As the American economy grew,however, businessmen saw China -- with a population of four hundred million people -- as a great market for American products.

VOA: special.2010.07.29

Four percent of the world's population plays some form of football.

VOA: special.2010.06.09

"We are adding eighty-four million people to the population every year.

VOA: special.2009.09.22

Afghanistan has a population estimated at almost thirty-four million people.

VOA: special.2009.08.18

They have predicted that up to one fifth of the Australian population about four million people could be infected by the swine flu virus.

VOA: standard.2009.05.30