SN4 ""

No	Pattern	Freq
1	[prep] about [num] years	371
2	[prep] about [adj] years	371
3	for about [adj] years	242
4	of about [adj] years	61
5	[prep] about two years	55
6	[prep] about two years	55
7	[prep] about three years	35
8	[prep] about three years	35
9	[prep] about ten years	28
10	[prep] about ten years	28
11	[prep] about five years	26
12	[prep] about five years	26
13	[prep] about four years	26
14	[prep] about four years	26
15	after about [adj] years	17
16	[prep] about 20 years	15
17	[prep] about 20 years	15
18	[prep] about six years	14
19	[prep] about six years	14
20	[prep] about seven years	12
21	until about [adj] years	12
22	[prep] about 10 years	12
23	[prep] about seven years	12
24	[prep] about 10 years	12
25	[prep] about fifteen years	11
26	by about [adj] years	11
27	[prep] about fifteen years	11
28	at about [adj] years	10
29	[prep] about nine years	8
30	[prep] about thirty years	8