Can you help me in solving the following linear modelling problem?

In 1978, 34.1% of American adults described themselves as regular cigarette smokers. By 1998, only 24.5% of American adults described themselves as regular cigarette smokers. How can I write a linear equation that models this decline in smoking. Let x represent the number of years after 1978 and let y represent the percentage of American adults who described themselves as regular cigarette smokers.