none 

Statements about this table:
for block i , there be zero unusable satellite
with 0 retired and less than 1 launch failure , the average number of not usable be 0
block i have launch more than 11 time with less than 10 retired
there be 6 block 's not usable
block
launched
operational
not usable
retired
launch failures
block i
11
0
0
10
1
block ii
9
0
0
9
0
block iia
19
8
1
10
0
block iir
13
12
0
0
1
block
launched
operational
not usable
retired
launch failures
block iirm
8
7
0
1
0
block iif
4
4
0
0
0
total
64
31
1
30
2