Chemical Equilibrium

Consider the reaction A⇌B at 1000K. At time 't', the temperature of the system was increased to 2000K and the system was allowed to reach equilibrium. Throughout this experiment the partial pressure of A was maintained at 1 bar. Given below is the plot of the partial pressure of B with time. What is the ratio of the standard Gibbs energy of the reaction at 1000K to that at 2000K?