data在某一個時間段固定不變：fixed in time
在一系列的時間段中轉變：changes over time
持續變化的data在不同情況下:
增加：increase / raise / rise / go up ...
減少：decrease / grow down / drop / fall ...
波動：fluctuate / rebound / undulate / wave ...
穩定：remain stable / stabilize / level off ...
最常用的兩種表達法：
動詞 + 副詞形式
形容詞 + 名詞形式
1. Verb+Adverb form
The number of XXX
+increase/jump/rise/decrease/drop/fall/fluctuate...
+insignificantly/significantly/slightly/suddenly/rapidly/dramatically/sharply/steeply/steadily/gradually/slowly...
+from to / between and
2. Adjective+Noun form
There was a sudden/rapid/dramatic/significant/sharp/steep/steady/gradual/slow/slight
+increase/jump/rise/decrease/drop/fall/fluctuation
+in the number of XXX from to / between and
描述穩定的data：
The number of XXX remained steady/stable from to / between and
The number of XXX stayed the same from to / between and