SN4 ""

No	Pattern	Freq
1	[noun] over a [adj] period	307
2	[noun] over a [adj] period	289
3	[noun] over a [adj] period	280
4	[noun sg] over a [adj] period	181
5	[noun] over a long period	120
6	[noun pl] over a [adj] period	105
7	[noun] over a long period	95
8	[noun] over a [adj -er] period	27
9	[noun] over a longer period	25
10	[noun] over an [adj] period	18
11	[noun] over a five-year period	13
12	[noun] over a five-year period	13
13	[noun] over a prolonged period	12
14	[noun] over a prolonged period	12
15	[n mass] over a [adj] period	11
16	[noun prp] over a [adj] period	10
17	[noun] over a three-year period	9
18	[noun] over a three-year period	9
19	[noun] over a extended period	8
20	[noun] over a short period	8
21	[noun] over a two-year period	8
22	[noun] over a extended period	8
23	[noun] over a two-year period	8
24	[noun] over a short period	7
25	[noun] over a given period	7
26	[noun] over a given period	7
27	[noun] over a four-year period	7
28	[noun] over a four-year period	7
29	[noun] over a lengthy period	6
30	[noun] over a lengthy period	6