SN4 ""

No	Pattern	Freq
1	over a [adv] [adj] period	31
2	over a [adv] [adj] period	31
3	over a [adj] [adj] period	10
4	over a much [adj] period	10
5	over a much [adj] period	10
6	over a [num] [adj] period	6
7	over a very [adj] period	6
8	over a very [adj] period	6
9	over a relatively [adj] period	5
10	over a relatively [adj] period	5
11	[noun] over a [adj] period	289
12	[noun sg] over a [adj] period	172
13	[noun pl] over a [adj] period	98
14	[verb] over a [adj] period	86
15	[vb pp] over a [adj] period	83
16	[adv] over a [adj] period	43
17	[adv] over a [adj] period	29
18	[adj] over a [adj] period	27
19	[conj] over a [adj] period	17
20	[adv prt] over a [adj] period	14
21	[adj] over a [adj] period	13
22	[coord] over a [adj] period	11
23	[n mass] over a [adj] period	10
24	[num] over a [adj] period	9
25	[noun prp] over a [adj] period	9
26	out over a [adj] period	6
27	that over a [adj] period	6
28	million over a [adj] period	6
29	out over a [adj] period	6
30	[that] over a [adj] period	6