Anyone relying purely on the State Pension to fund their retirement needs their head examining. Even if you get the maximum new State Pension, you'll be getting just £12,547 this year. You'll need a fair bit more to enjoy a 'moderate' retirement, let alone a comfortable one. I've chosen that figure because once added to the state pension, it would lift a single person's income to £32,700, producing a 'moderate' retirement. Over the last decade, the average Stocks and Shares ISA has delivered a total return of 9.64% a year, with dividends reinvested.