Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Whitworth size (in) | Core diameter (in) | Threads per inch | Pitch (in) | Tapping drill size |
| --- | --- | --- | --- | --- |
| 1/16 | 0.0411 | 60 | 0.0167 | Number Drill 56 (1.2 mm) |
| 3/32 | 0.0672 | 48 | 0.0208 | Number Drill 49 (1.85 mm) |
| 1/8 | 0.0930 | 40 | 0.025 | Number Drill 39 (2.55 mm) |
| 5/32 | 0.1162 | 32 | 0.0313 | Number Drill 30 (3.2 mm) |
| 3/16 | 0.1341 | 24 | 0.0417 | Number Drill 26 (3.7 mm) |
| 7/32 | 0.1654 | 24 | 0.0417 | Number Drill 16 (4.5 mm) |
| 1/4 | 0.1860 | 20 | 0.05 | Number Drill 9 (5.1 mm) |
| 5/16 | 0.2414 | 18 | 0.0556 | Letter Drill F (6.5 mm) |
| 3/8 | 0.2950 | 16 | 0.0625 | 5/16 in (7.94 mm) |
| 7/16 | 0.3460 | 14 | 0.0714 | Letter Drill U (9.3 mm) |
| 1/2 | 0.3933 | 12 | 0.0833 | Letter Drill Z (10.5 mm) |
| 9/16 | 0.4558 | 12 | 0.0833 | 12.1 mm (0.4764 in) |
| 5/8 | 0.5086 | 11 | 0.0909 | 13.5 mm (0.5315 in) |
| 11/16 | 0.5711 | 11 | 0.0909 | 15 mm (0.5906 in) |
| 3/4 | 0.6219 | 10 | 0.1 | 16.27 mm (0.6406 in) |
| 13/16 | 0.6845 | 10 | 0.1 | 18 mm (0.7087 in) |
| 7/8 | 0.7327 | 9 | 0.1111 | 19.25 mm (0.7579 in) |
| 15/16 | 0.7953 | 9 | 0.1111 | 20.75 mm (0.8169 in) |
| 1 | 0.8399 | 8 | 0.125 | 22 mm (0.8661 in) |
| 1 1/8 | 0.9420 | 7 | 0.1429 |  |
| 1 1/4 | 1.0670 | 7 | 0.1429 |  |
| 1 1/2 | 1.2866 | 6 | 0.1667 |  |
| 1 3/4 | 1.4939 | 5 | 0.2 |  |
| 2 | 1.7154 | 4.5 | 0.2222 |  |
| 2 1/2 | 2.180 | 4 | 0.250 |  |
Question:
how many more threads per inch does the 1/16th whitworth size have over the 1/8th whitworth size?
Answer:
20