The percentage of the annual decrease in infant mortality rate since 1990 is ______.

(30[A]) The infant mortality rate in China has declined notably since the beginning of the 1990s, according to China’s new white paper on children’s conditions. (29[A]) The average decrease in infant mortality in the country is 6.5 percent a year since 1990. The mortality rate of children under five years old has been tailing off by 5.85 percent annually, the white paper says. The white paper, entitled "The Situation of children in China" and issued by the Information Office of the State Council says that so far, no other country in the world with an annual per capita income approximate to China’s has attained such rapid decreases.