Noting the confidence intervals and margins of error noted in the data below, it is likely that Canada, Australia and New Zealand have almost the same smoking prevalence; that England may have slightly higher because of it not counting combustible tobacco other than cigarettes and roll-your-own tobacco, and that the USA has the highest smoking prevalence of the five nations.

    Australia:(2019 AIHW ages ≥14 and  ≥18): (all combustible tobacco users, at any smoking frequency –people who reported smoking cigarettes daily, weekly, monthly or less than monthly) ≥14yrs: 14.0% (margin of error 0.6); ≥18 yrs: 14.7% (margin of error 0.7%) Daily smoking by 11%.
    Canada:(2019 Canadian Tobacco and Nicotine Survey ≥15yrs  14% (Only past 30-day use of any tobacco product -- including chewing tobacco)
    New Zealand:2018 Current smoking (smoke at least monthly, and have smoked more than 100 cigarettes in their whole life time) among persons aged  ≥15): 14.2%  (CIs: 13.4-15.0) (Māori adults 34% (31.1-37.1) (cigarettes & RYO only at any smoking frequency)
    UK:(2019 Office of National Statistics; ages  ≥ 18): 14.1%  “who smoke cigarettes nowadays”)
    USA: (2018 NHIS ages ≥ 18): 16.5% (CIs 15.9-17.2) (all combustible tobacco users at any smoking frequency “every day or some days”