The Swiss are voting on Sunday on whether the state should disburse a 13th monthly pension payment each year in a referendum likely to be close, according to pre-election polling. While surveys indicate a small majority in favour, the measure could fall at the second hurdle, which requires a majority of the 26 cantons to be in favour. There is often a majority in several smaller cantons against additional burdens on the state. Also up for a vote on Sunday is an increase in the retirement age from the current 65 years. Pre-election polling suggests this measure will fail. The pensions issue has…