An exact % is given in the Encyclopedia of Bridge.

Here is a rough % table generated by computer simulation of 10 million hands.

**** total distribution

4432 = 2157319 5332 = 1551839 5431 = 1294354 5422 = 1057365 4333 = 1051898 6322 = 564302
6421 = 468697 6331 = 344400 5521 = 318014 4441 = 299428 7321 = 187712 6430 = 132685
5440 = 124347 5530 = 89786 6511 = 70749 6520 = 65127 7222 = 51175 7411 = 39181
7420 = 36079 7330 = 26370 8221 = 19089 8311 = 11867 8320 = 10691 7510 = 10917
6610 = 7407 8410 = 4478 9211 = 1837 9310 = 1000 9220 = 792 7600 = 514
8500 = 316 10210 = 100 9400 = 110 10111 = 41 10300 = 12 11110 = 0
11200 = 2 12100 = 0
total count is 10000000

4432 = 21.57% 5332 = 15.52% 5431 = 12.94% 5422 = 10.57% 4333 = 10.52% 6322 = 5.64%
6421 = 4.69% 6331 = 3.44% 5521 = 3.18% 4441 = 2.99% 7321 = 1.88% 6430 = 1.33%
5440 = 1.24% 5530 = 0.90% 6511 = 0.71% 6520 = 0.65% 7222 = 0.51% 7411 = 0.39%
7420 = 0.36% 7330 = 0.26% 8221 = 0.19% 8311 = 0.12% 8320 = 0.11% 7510 = 0.11%
6610 = 0.07% 8410 = 0.04% 9211 = 0.02% 9310 = 0.01% 9220 = 0.01% 7600 = 0.01%
8500 = 0.00% 10210 = 0.00% 9400 = 0.00% 10111 = 0.00% 10300 = 0.00% 11110 = 0.00%
11200 = 0.00% 12100 = 0.00%

A very interesting table of hand pattern evaluation is given by Thomas's Bridge Fantasia

Many unique information related to statistical analysis of bridge hands including Law of total tricks and hand evaluations.

`I added more information to the table on a spread sheet where `
`total is the sum of offence and defense, and diff is offence - defense`
 Best NT Suit Pattern Off Def total diff Off Def total diff Off Def total diff 4-3-3-3 7.8 4.59 12.39 3.21 6.15 6.83 12.98 -0.68 7.76 4.59 12.35 3.17 4-4-3-2 8.09 4.67 12.76 3.42 6.1 6.8 12.9 -0.7 8.07 4.68 12.75 3.39 5-3-3-2 8.14 4.52 12.66 3.62 6.07 6.9 12.97 -0.83 8.13 4.53 12.66 3.6 5-4-2-2 8.41 4.56 12.97 3.85 6.01 6.87 12.88 -0.86 8.4 4.57 12.97 3.83 6-3-2-2 8.51 4.3 12.81 4.21 6 7.16 13.16 -1.16 8.5 4.32 12.82 4.18 4-4-4-1 8.62 4.83 13.45 3.79 6.09 6.79 12.88 -0.7 8.61 4.85 13.46 3.76 5-4-3-1 8.69 4.68 13.37 4.01 6.03 6.88 12.91 -0.85 8.68 4.7 13.38 3.98 6-3-3-1 8.78 4.43 13.21 4.35 6.03 7.17 13.2 -1.14 8.77 4.46 13.23 4.31 7-2-2-2 8.91 4.03 12.94 4.88 5.95 7.54 13.49 -1.59 8.91 4.05 12.96 4.86 6-4-2-1 9.02 4.41 13.43 4.61 5.97 7.13 13.1 -1.16 9.02 4.45 13.47 4.57 5-5-2-1 9.03 4.53 13.56 4.5 5.94 6.95 12.89 -1.01 9.03 4.56 13.59 4.47 7-3-2-1 9.14 4.09 13.23 5.05 5.94 7.53 13.47 -1.59 9.13 4.13 13.26 5 5-4-4-0 9.38 4.8 14.18 4.58 6.19 6.99 13.18 -0.8 9.37 4.84 14.21 4.53 6-4-3-0 9.51 4.59 14.1 4.92 6.18 7.25 13.43 -1.07 9.51 4.63 14.14 4.88 5-5-3-0 9.51 4.66 14.17 4.85 6.12 7.07 13.19 -0.95 9.51 4.71 14.22 4.8 8-2-2-1 9.57 3.76 13.33 5.81 5.87 7.96 13.83 -2.09 9.57 3.8 13.37 5.77 6-5-1-1 9.61 4.28 13.89 5.33 5.83 7.15 12.98 -1.32 9.61 4.32 13.93 5.29 7-3-3-0 9.65 4.29 13.94 5.36 6.16 7.64 13.8 -1.48 9.64 4.35 13.99 5.29 7-4-1-1 9.67 4.16 13.83 5.51 5.98 7.61 13.59 -1.63 9.66 4.2 13.86 5.46 8-3-1-1 9.83 3.84 13.67 5.99 5.96 8.11 14.07 -2.15 9.82 3.88 13.7 5.94 6-5-2-0 9.88 4.38 14.26 5.5 6.03 7.27 13.3 -1.24 9.88 4.43 14.31 5.45 7-4-2-0 9.89 4.25 14.14 5.64 6.14 7.69 13.83 -1.55 9.88 4.3 14.18 5.58 8-3-2-0 10 3.87 13.87 6.13 6.08 8.07 14.15 -1.99 9.99 3.92 13.91 6.07 9-2-1-1 10.19 3.31 13.5 6.88 5.61 8.34 13.95 -2.73 10.19 3.36 13.55 6.83 8-4-1-0 10.49 3.88 14.37 6.61 6.06 8.16 14.22 -2.1 10.49 3.92 14.41 6.57 7-5-1-0 10.5 4.11 14.61 6.39 6 7.75 13.75 -1.75 10.5 4.15 14.65 6.35 6-6-1-0 10.51 4.08 14.59 6.43 5.83 7.4 13.23 -1.57 10.51 4.14 14.65 6.37 9-3-1-0 10.56 3.39 13.95 7.17 5.63 8.31 13.94 -2.68 10.55 3.44 13.99 7.11 9-2-2-0 10.56 3.54 14.1 7.02 5.99 8.73 14.72 -2.74 10.55 3.6 14.15 6.95 10-1-1-1 10.89 3.33 14.22 7.56 4.89 9.11 14 -4.22 10.89 3.56 14.45 7.33 10-2-1-0 10.97 3.21 14.18 7.76 5.95 9.24 15.19 -3.29 10.97 3.24 14.21 7.73 7-6-0-0 11.18 3.8 14.98 7.38 6.14 7.59 13.73 -1.45 11.18 3.86 15.04 7.32 9-4-0-0 11.24 3.41 14.65 7.83 6.17 8.62 14.79 -2.45 11.24 3.41 14.65 7.83 8-5-0-0 11.26 3.7 14.96 7.56 6.02 7.98 14 -1.96 11.26 3.71 14.97 7.55 11-1-1-0 12 4 16 8 6 6 12 0 12 4 16 8 10-3-0-0 13 6 19 7 13 13 26 0 13 6 19 7
`The total column is a good valuation of the combined offence and defense value of the hand.`
`The bigger the diff column value the more you should bid. You have an offence oriented pattern.`