See my post 29 to this link for the statistics of a fairly frequently cited survey conducted in Canada. The lifetime risk is more than either you or I initially sited. But a google search or medpub search will give lots of numbers that are slightly higher than your 7% figure, usually around 11%.
I have found it difficult to find statistics on lung cancer rates in Google searches but I may try your medpub suggestion sometime. Neither gov sites (NDHS??? NHSD???) or American Cancer Society seem to have them. That makes me suspect an agenda not a genuine regard for disseminating truth. The same lack of info is apparent when one tries to find out how many women die from legal abortions. I know they collect the numbers.