SN4 ""

No	Pattern	Freq
1	period [prep] [adj] years	346
2	period of [adj] years	337
3	period of [adj] years	337
4	period [prep] [num] years	327
5	period [prep] five years	48
6	period [prep] five years	48
7	period [prep] two years	44
8	period [prep] two years	44
9	period [prep] three years	44
10	period [prep] three years	44
11	period [prep] [det] years	18
12	period [prep] ten years	17
13	period [prep] ten years	17
14	period [prep] four years	16
15	period [prep] four years	16
16	period [prep] twenty years	13
17	period [prep] twenty years	13
18	period [prep] six years	12
19	period [prep] six years	12
20	period [prep] 10 years	11
21	period [prep] 10 years	11
22	period [prep] seven years	10
23	period [prep] seven years	10
24	period [prep] several years	9
25	period [prep] several years	9
26	period [prep] 20 years	8
27	period [prep] 20 years	8
28	period [prep] many years	6
29	period [prep] 15 years	6
30	period [prep] many years	6