SN4 ""

No	Pattern	Freq
1	[prep] at [adv] a year	39
2	[prep] at [adv] a year	39
3	for at [adv] a year	34
4	for at [adv] a year	34
5	[verb] at [adv] a year	10
6	[noun] at [adv] a year	5
7	at [adv] [adv] a year	46
8	at [adv] [adv] a year	46
9	at least [adv] a year	45
10	at least [adv] a year	45
11	at [adv] [adv] a year	46
12	at [adv] [adv] a year	46
13	at [adv] once a year	33
14	at [adv] once a year	33
15	at [adv] [noun] a year	24
16	at [adv] [n mass] a year	24
17	at [adv] twice a year	12
18	at [adv] twice a year	12
19	at [adv] [adj] a year	7
20	at [adv] [num] a year	6
21	at [adv] a [adj] year	15
22	at [adv] a [num] year	9
23	at [adv] a hundred year	5
24	at [adv] a hundred year	5
25	at [adv] a year [conj]	7
26	at [adv] a year [adv]	7
27	at [adv] a year [prep]	6
28	at [adv] a year [adv]	6
29	at [adv] a year [verb]	6
30	at [adv] a year [coord]	6