How you assess quit attempts for smoking makes a big difference to your results.
Cunningham
John A
JA
Selby
Peter L
PL
D002170:Canada; D006801:Humans; D015995:Prevalence; D012907:Smoking / Q000453:epidemiology*; D016540:Smoking Cessation / Q000706:statistics & numerical data*; D006113:United Kingdom