Volatility surfaces

So I'm learning about volatility smiles and volatility surfaces from Hull's Options, Futures and Other Derivatives . On p. 459, there is the following table (Table 20.2) of a volatility surface: Maturity 0.90 0.95 1.00 1.05 1.10 1 month 14.2 13.0 12.0 13.1 14.5 3 month 14.0 13.0 12.0 13.1 14.2 6 month 14.1 13.3 12.5 13.4 14.3 1 year 14.7 14.0 13.5 14.0 14.8 2 year 15.0 14.4 14.0 14.5 15.1 5 year 14.8 14.6 14.4 14.7 15.0 The columns denote different values for $K/S_0$ , where $K$ is the strike pr