Easiest way if Year 1 is in cell A3 is to make cell B3=A3*1.02 and drag it across as many cells as you want years.

ETA - I changed to 1.02 for 2%. I had read 20% at first

Quick and dirty:
1) Type "10" into cell A1;
2) Into cell A2, type "=A1*1.02" (without the quotes);
3) Click on the little square at the bottom right of cell A2 and drag it straight down to cell A20;
4) Release the mouse button. Voila.

10 10.2 10.404 10.61208 10.82432 11.04081 11.26162 11.48686 11.71659 11.95093 12.18994 12.43374 12.68242 12.93607 13.19479 13.45868 13.72786 14.00241 14.28246 14.56811

Perfect.

Thanks all.