Anyone knows the thresholds for endurance that make you gain more hit points per level?

Here's what I figured for MM1 so far through experimentation:

8,13,15,17,19,*21,*24

I'm not 100% sure for 21 and 24.

From Andrew Schultz's FAQs:

MM1:
1- 4 = -3
5- 6 = -2
7- 8 = -1
9-12 = 0
13-14 = +1
15-16 = +2
17-18 = +3
19-20 = +4
21-23 = +5
24-26 = +6
27-29 = +7
30-39 = +8
40+ = +9

MM2:
11-12 0
13-14 1
15-16 2
17-18 3
19-21 4
22-25 5
26-29 6
30-44 7
45-59 8
60-74 9
75-89 10
90-104 11
105-119 12
120-134 13
135-149 14
150-174 15
175-199 16
200-224 17
225-249 18

Thanks very much, that confirms the 19-21-24 breakpoint suspicion I had, BUT the 8 endurance breakpoint is incorrect - I tested it myself. 8 END gives a 12 HP knight, same as 9-12 endurance. 6 and 7 endurance produce a 11 HP knight.

So,

MM1:
1- 4 = -3
5- 6 = -2
7- 8 = -1

Should be
1-3=-3
4-5=-2
6-7=-1