KEYWORDS: describe, trend
(subject) fluctuate between… and…
there be fluctuation in (subject), between… and…
NOTE between (lowest value) and (highest value)
From 1990 to 2010, the amount of energy derived from hydropower fluctuated between 3g units and 7q units.
From 1990 to 2010, there was fluctuation between 3g units and 7g units in the amount of energy derived from hydropower.