In all actions against a railroad company, operating a railroad in whole or part within this state, for personal injury to an employee or where such injuries have resulted in his death, the fact that he was guilty of contributory negligence shall not bar a recovery when such negligence was slight and that of the employer greater in comparison. But the damages must be diminished by the jury in proportion to the amount of negligence attributable to such employee. All questions of negligence and contributory negligence are for the jury.