Is Google Growing Linearly ?

Could make sense if (1) a fixed percentage of total ad spending is moved to google every year and (2) the amount not yet moved over is much smaller than the total amount that will be eventually moved. Not too unreasonable. Fit is minimal-relative-error (least squares). Extrapolation to 2015 gives 48-56 Bio USD in annual sales and 10% year-on-year sales growth, to which the overall growth in ad spending may contribute a few percent.