How to access to the cv_score of the fitted pipeline

I am doing regression for the Boston Housing Price dataset using TPOTRegressor.
Since I am comparing the score of TPOTRegressor with other models, defined by hand, I would like to access to the cv_score of the best model, the one saved as "fitted_pipeline_". How can I access it?
Because with TPOTRegressor function, I can define the cross-validation and I want to get the score of this cross-validation.
I saw that the attribute "evaluated_individuals_" allows to look at the "internal_cv_score"of all models, but I would like to know if there is an easier and faster way to get the best cv_score, something like: tpot.best_cv_score
How can I do that?
Thank you very much