That link said they got their info from the American Cancer Society. Here is a link to the ACS page that has that same chart. It isn't 5 years for every 1 year, but it definitely isn't 10 years either:

http://www.cancer.org/docroot/PED/content/PED_10_2x_Questions_About_Smoking_Tobacco_and_Health.asp

After 5: Stroke risk is reduced to that of a nonsmoker. (US Surgeon General's Report, 1990, p.79)

After 10 years: The lung cancer death rate is about half that of a continuing smoker's. The risk of cancer of the mouth, throat, esophagus, bladder, kidney, and pancreas decreases. (US Surgeon General's Report, 1990, pp.110, 147, 152, 155, 159, 172)

After 15 years: The risk of coronary heart disease is that of a nonsmoker's. (US Surgeon General's Report, 1990, p.79)

It’s important to note that the extent to which these risks decrease depends on how much the person smoked, the age the person started smoking, and the amount of inhalation.