Complex sentence: In addition, the lowest available transfer energy varies on a roughly 16-year cycle, with a minimum in the 1969 and 1971 launch windows, rising to a peak in the late 1970s, and hitting another low in 1986 and 1988.
Split into simpler sentences: In addition, the lowest available transfer energy varies on a roughly 16-year cycle. For example, there was a minimum in the 1969 and 1971 launch windows, rising to a peak in the late 1970s, and hitting another low in 1986 and 1988.