Low hit rate

I've a problem, I've 20 sibling but I got a very low hit rate :

# Outgoing requests by status
status request % kByte % sec
kB/sec
--------------------------------- -------- ------ --------- ------ ----
-------
DIRECT Fetch from Source 53071 96.65 366676 96.33 35
0.20
 TIMEOUT_DIRECT 27212 49.56 195876 51.46 40
0.18
 DIRECT 25859 47.09 170800 44.87 30
0.22
HIT on Sibling or Parent Cache 1839 3.35 13966 3.67 5
1.39
 SIBLING_HIT 1839 3.35 13966 3.67 5
1.39
PARENT 0 0.00 0 0.00 0
0.00
--------------------------------- -------- ------ --------- ------ ----
-------
Sum 54910 380642 34
0.20

And they got a good hit rate comparet to mine:

# Incoming UDP-requests by status
status request % kByte % msec
kB/sec
--------------------------------- -------- ------ --------- ------ ----
-------
HIT 31664 14.87 2107 14.36 0
665.57
 UDP_HIT 31664 14.87 2107 14.36 0
665.57
MISS 181233 85.13 12572 85.64 0
693.69
 UDP_MISS 180797 84.92 12543 85.45 0
693.75
 UDP_DENIED 436 0.20 29 0.20 0
665.41
--------------------------------- -------- ------ --------- ------ ----
-------
Sum 212897 14679 0
689.50

# Incoming TCP-requests by status
status request % kByte % sec
kB/sec
--------------------------------- -------- ------ --------- ------ ----
-------
HIT 43753 45.82 166391 31.39 3
1.36
 TCP_HIT 20147 21.10 138766 26.18 4
1.55
 TCP_IMS_HIT 17463 18.29 5750 1.08 0
3.83
 TCP_REFRESH_HIT 4404 4.61 18114 3.42 7
0.62
 TCP_MEM_HIT 1366 1.43 3565 0.67 0
47.01
 TCP_NEGATIVE_HIT 225 0.24 195 0.04 0
15.65
 TCP_REF_FAIL_HIT 148 0.15 0 0.00 15
0.00
MISS 50357 52.73 362528 68.39 36
0.20
 TCP_MISS 48550 50.84 350193 66.06 37
0.20
 TCP_REFRESH_MISS 1806 1.89 12334 2.33 29
0.24
 TCP_SWAPFAIL_MISS 1 0.00 1 0.00 24
0.04
ERROR 1383 1.45 1164 0.22 0
7.89
 TCP_DENIED 893 0.94 880 0.17 0
26.38
 TCP_MISS 473 0.50 262 0.05 0
2.38
 NONE 17 0.02 22 0.00 0
5.30
--------------------------------- -------- ------ --------- ------ ----
-------
Sum 95493 530083 20
0.27

I tried to increse the hit rate using the refresh pattern suggested by
AUIX but got no increment:

refresh_pattern \.gif$ 10080 90% 43200
refresh_pattern \.jpg$ 10080 90% 43200
refresh_pattern \.bom\.gov\.au 30 20% 120
refresh_pattern \.html$ 480 50% 22160
refresh_pattern \.htm$ 480 50% 22160
refresh_pattern \.class$ 10080 90% 43200
refresh_pattern \.zip$ 10080 90% 43200
refresh_pattern \.jpeg$ 10080 90% 43200
refresh_pattern \.mid$ 10080 90% 43200
refresh_pattern \.shtml$ 480 50% 22160
refresh_pattern \.exe$ 10080 90% 43200
refresh_pattern \.thm$ 10080 90% 43200
refresh_pattern \.wav$ 10080 90% 43200
refresh_pattern \.txt$ 10080 90% 43200
refresh_pattern \.cab$ 10080 90% 43200
refresh_pattern \.au$ 10080 90% 43200
refresh_pattern \.mov$ 10080 90% 43200
refresh_pattern \.xbm$ 10080 90% 43200
refresh_pattern \.ram$ 10080 90% 43200
refresh_pattern \.avi$ 10080 90% 43200
refresh_pattern \.chtml$ 480 50% 22160
refresh_pattern \.thb$ 10080 90% 43200
refresh_pattern \.dcr$ 10080 90% 43200
refresh_pattern \.bmp$ 10080 90% 43200
refresh_pattern \.phtml$ 480 50% 22160
refresh_pattern \.mpg$ 10080 90% 43200
refresh_pattern \.pdf$ 10080 90% 43200
refresh_pattern \.art$ 10080 90% 43200
refresh_pattern \.swf$ 10080 90% 43200
refresh_pattern \.mp3$ 10080 90% 43200
refresh_pattern \.ra$ 10080 90% 43200
refresh_pattern \.spl$ 10080 90% 43200
refresh_pattern \.viv$ 10080 90% 43200
refresh_pattern \.doc$ 10080 90% 43200
refresh_pattern \.gz$ 10080 90% 43200
refresh_pattern \.Z$ 10080 90% 43200
refresh_pattern \.tgz$ 10080 90% 43200
refresh_pattern \.tar$ 10080 90% 43200
refresh_pattern \.vrm$ 10080 90% 43200
refresh_pattern \.vrml$ 10080 90% 43200
refresh_pattern \.aif$ 10080 90% 43200
refresh_pattern \.aifc$ 10080 90% 43200
refresh_pattern \.aiff$ 10080 90% 43200
refresh_pattern \.arj$ 10080 90% 43200
refresh_pattern \.c$ 10080 90% 43200
refresh_pattern \.cpt$ 10080 90% 43200
refresh_pattern \.dir$ 10080 90% 43200
refresh_pattern \.dxr$ 10080 90% 43200
refresh_pattern \.hqx$ 10080 90% 43200
refresh_pattern \.jpe$ 10080 90% 43200
refresh_pattern \.lha$ 10080 90% 43200
refresh_pattern \.lzh$ 10080 90% 43200
refresh_pattern \.midi$ 10080 90% 43200
refresh_pattern \.movie$ 10080 90% 43200
refresh_pattern \.mp2$ 10080 90% 43200
refresh_pattern \.mpe$ 10080 90% 43200
refresh_pattern \.mpeg$ 10080 90% 43200
refresh_pattern \.mpga$ 10080 90% 43200
refresh_pattern \.pl$ 10080 90% 43200
refresh_pattern \.ppt$ 10080 90% 43200
refresh_pattern \.ps$ 10080 90% 43200
refresh_pattern \.qt$ 10080 90% 43200
refresh_pattern \.qtm$ 10080 90% 43200
refresh_pattern \.ras$ 10080 90% 43200
refresh_pattern \.sea$ 10080 90% 43200
refresh_pattern \.sit$ 10080 90% 43200
refresh_pattern \.tif$ 10080 90% 43200
refresh_pattern \.tiff$ 10080 90% 43200
refresh_pattern \.snd$ 10080 90% 43200
refresh_pattern \.wrl$ 10080 90% 43200
refresh_pattern ^ftp:// 480 60% 22160
refresh_pattern ^gopher:// 30 20% 120
refresh_pattern . 480 50% 22160

Any idea ?

Thank you.

---
Gianluigi Salerno - TELNET S.r.L.        Phone  : +39-0382-529751 
TELNET e' associata ad AIIP              Fax    : +39-0382-528074 
I-27100 V. Buozzi, 5 - Pavia, Italy      e-mail : gsalerno@telnetwork.it