Table 2. Distributions of 9594 families by mutation count under different lethality intervals.

Mutations	[99–100%]	[98–99%)	[97–98%)
Allelism test  with α = 0.1
0	8459	8391	8296
1	1052	1134	1240
2	81	66	56
3	2	3	2
mt	1220	1275	1358
nm	2673	10,766	17,342
$\tilde{\mu }$	0.0098	0.0396	0.0638
Allelism test  with α = 0.5
0	8304	8273	8265
1	1174	1219	1232
2	112	95	93
3	4	7	4
mt	1410	1430	1430
nm	2897	11,328	16,574
$\tilde{\mu }$	0.0107	0.0417	0.0610

m_t, total number of mutations; n_m, total number of mutants; $\tilde{\mu }$, overall mutation rate estimated by Equation (6).