Eg: The number of aged people over 65 increased significantly from 1940-2000.
The number of aged people over 65 dropped slightly from 1960-1980.
The number of aged people over 65 fluctuated between 1 million and 1.2 million from 1940-1950.
The number of aged people over 65 remained stable from 1930-1940.
句式二： There be + 形容词 + 表示趋势的名词 + in+ 变化的主体 + 时间区间
Eg: There was an significant increase in the number of aged people over 65 from 1940-2000.
There was a slight decline in the number of aged people over 65 from 1960-1980.
There was a fluctuation between 1 million and 1.2 million from 1940-1950.
climb, go up, ascend, shoot up，creep up, surge, boom, accrue,
leap, soar, jump, increase, rally, rise, rocket, improve,
go down, fall, fall off, drop, slump, decline, decrease, plummet, slide, slip,
shrink, dip, reduce, descend, sink, subside, ebb, creep down,
top out, peak, reach a peak, reach the highest point, peak at..,
level out, even out, remain stable/still/steady, stay constant,
keep its stability, remain unchanged…
significantly, markedly, surprisingly, noticeably, substantially…
steadily, smoothly, slowly, marginally, gradually, moderately, mildly…
fluctuate, witness/display/demonstrate a fluctuation,
go ups and downs, increase with fluctuation(波动式增长)