May is the beginning of blockbuster season at the movie theaters. The following chart gives the May box office receipts in the United States (in millions of USD) for 8 years in the 1990s

year	1991	1992	1993	1994	1995	1996	1997	1998
receipts	273	316	297	323	373	453	472	510

Find a linear regression model which predicts May box office receipts as a function of

the year. Give the equation of the fitted model.