对机队按5年机龄间隔进行了分组，从统计情况来看，随着机队机龄的逐步增加，25%、75%和中位数故障百次率增量均呈现慢慢向上偏移的趋势，尤其是机龄在15-20年后将会出现大幅度的突增。
count 22.000000
mean 34.897930
std 55.212569
min -37.710540
25% 1.010471
50% 28.704239
75% 50.938856
max 221.085294
Name: 百次率差值, dtype: float64
count 117.000000
mean 30.661771
std 40.349511
min -68.604388
25% 4.493881
50% 32.850640
75% 59.893330
max 113.274027
Name: 百次率差值, dtype: float64
count 46.000000
mean 34.903735
std 57.636321
min -78.434917
25% 5.193854
50% 36.474544
75% 59.285079
max 168.139237
Name: 百次率差值, dtype: float64
count 18.000000
mean 71.439500
std 122.689369
min -46.540578
25% 8.188804
50% 41.999193
75% 81.487403
max 510.527058
Name: 百次率差值, dtype: float64
count 6.000000
mean 69.129843
std 87.706618
min -72.301656
25% 21.176344
50% 111.869516
75% 126.492887
max 141.029048
Name: 百次率差值, dtype: float64
