From 1985 to 2001, the prevalence rose 100 percent.

"The prevalence of positive serum tests in such areas rises to over forty percent within 0.5 to 5 years."

Among people in their 30's, the prevalence rose to 3.7 percent from 2.1 percent.

The prevalence of contraceptive use has risen markedly over the decades.

And experts say that the prevalence of allergies in adults is rising.

Adult prevalence also rose from 0.29% in 2008 to 0.31% in 2009.

Among those born in 1997, who are now turning 6, the prevalence has risen to one in 323.

From 1980 to 1994, the prevalence of asthma rose by 75 percent, and scientists do not know why.

Unfortunately, as the government increased efforts to help families losing their homes, the prevalence of fraud rose simultaneously.

The prevalence of vertigo rises with age and is about two to three times higher in women than in men.