original: such near-perihelion oppositions occur on a regular cycle every twenty-two years , with the last occurring in 1991 and the next in 2013 .
simplifications: such near-perihelion oppositions occur on a regular cycle every twenty-two years , the last occurring in 1991 and the next in 2013 . such closeness to the sun oppositions occur on a regular cycle every twenty-two years , with the last happening in 1991 and the next in 2013 . such near-perihelion resistances occur on a regular cycle every twenty-two years , with the last happening in 1991 and the next in 2013 . these near perihelion oppositions occur regularly with the last concurring in 1991 and 2013 . such near-perihelion oppositions found on a regular cycle every twenty-two years , with the last occurring in 1991 and the next in 2013 . near-perihelion oppositons occur every twenty - two years , the last was in 1991 , the next will be in 2013 . such near-perihelion oppositions occur on a regular cycle once in every twenty years , with the last having occurred in 1991 and then in 2013 . such near-perihelion conflicts occur regularly every twenty-two years , with the last occurring in 1991 and the next in 2013 .