Credit card companies aggressively compete for credit card holders. The percentage of Americans having credit cards has increased in recent years, as shown in the following table. Percentage of Americans Having a Credit Card 1989 1992 1995 1998 2001 56.0 62.4 67.5 72.7 66.4 Year Percentage (a) Use these data to determine the linear least squares regression function with percentage having a credit card as a function of years since 1989 (x = 0 for 1989). (Round any numerical values to two decimal places.) f(x) = (b) Use the linear function to estimate the percentage having a credit card in 1985. (Round your answer to one decimal place.) % (c) Use the linear function to estimate the percentage having a credit card in 2004. (Round your answer to one decimal place.) % (d) According to the function, when will 100% of Americans have a credit card? (Round your answer to the nearest year.)