SN4 ""

No	Pattern	Freq
1	period of [adj] years	348
2	period [prep] [adj] years	346
3	period [prep] [num] years	335
4	period [prep] five years	51
5	period [prep] five years	51
6	period [prep] three years	47
7	period [prep] three years	47
8	period [prep] two years	45
9	period [prep] two years	45
10	period [prep] [det] years	21
11	period [prep] ten years	18
12	period [prep] ten years	18
13	period [prep] four years	16
14	period [prep] four years	16
15	period [prep] twenty years	13
16	period [prep] twenty years	13
17	period [prep] six years	12
18	period [prep] several years	12
19	period [prep] several years	12
20	period [prep] six years	12
21	periods [prep] [adj] years	11
22	period [prep] 10 years	11
23	period [prep] 10 years	11
24	period [prep] seven years	10
25	period [prep] seven years	10
26	period [prep] 20 years	8
27	period [prep] 20 years	8
28	period [prep] 15 years	6
29	period [prep] 15 years	6
30	period [prep] many years	6