What was the percentage change in the Weighted average share price (pence)?
{"Weighted average share price (pence)": {"2019": 163.1, "2018": 112.9}, "Weighted average exercise price (pence)": {"2019": 0.0, "2018": 0.0}, "Weighted average fair value (pence)": {"2019": 141.1, "2018": 95.1}, "Expected volatility (%)": {"2019": 31.6, "2018": 30.6}, "Option life (years): --  Performance Shares": {"2019": 3.0, "2018": 3.0}, "Option life (years): --  Options and SARs": {"2019": 10.0, "2018": 10.0}, "Option life (years): -- Risk free rate (%)": {"2019": 0.48, "2018": 0.88}, "Option life (years): -- Dividend yield (%)": {"2019": 2.5, "2018": 3.0}}
weighted_average_share_price_pence_2019 = df["Weighted average share price (pence)"]["2019"]
weighted_average_share_price_pence_2018 = df["Weighted average share price (pence)"]["2018"]
answer = ( weighted_average_share_price_pence_2019 - weighted_average_share_price_pence_2018 ) / weighted_average_share_price_pence_2018 * 100.0