A binary mixture with components $A$ and $B$ is to be separated in a distillation column to obtain $95$ mol$\%$ $A$ as the top product. The binary mixture has a constant relative volatility $\alpha _{AB}=2$. The column feed is a saturated liquid containing $50$ mol$\%$ $A$. Under the usual simplifying assumptions such as constant molal overflow, negligible heat loss, ideal trays, the minimum reflux ratio for this separation is _______________ (rounded off to one decimal place).