training rows 634 (churn rate 21.8%), test rows 656 (churn rate 30.9%)
   recency  orders_90  orders_all  spend_90  avg_gap  tenure  express_share  trend  churned
0       17          2           2     101.0    40.18      57           0.00    0.5        0
1        3          6           6     272.0    12.20      64           0.50    3.0        0
2        9          7           7     333.0     9.54      66           0.00    1.0        0
3       23          1           1      64.0    23.00      23           0.00    1.0        0
4        2          8           8     413.0    12.16      87           0.12    0.5        1
