10 year doesn't include the 1999-2000 bubble era, 15 year does. Those couple of years were among the best periods for VC returns ever, hence any period includin

10 year doesn't include the 1999-2000 bubble era, 15 year does. Those couple of years were among the best periods for VC returns ever, hence any period including them will have disproportionately high #s relative to other periods.