2. The number of stay-at-home fathers in Canada has been growing steadily. While the trend is not perfectly linear, it is fairly linear. Use the data from 1976 and 2010 to find an explicit formula for the number of stay-at-home fathers, then use it to predict the number if 2020. 

Year 1976 1984 1991 2000 2010 

Number of stay-at-home fathers 20,610 28,725 43,530 47,665 53,555