Refer to the following debt schedule:

ISSUE

QUANTITY

COUPON

YTM

15-yr Sr Debentures, due 2/15/2034

$467million

4.50%

3.60%

20-yr Sub Debentures, due 8/1/2030

$275million

7.25%

5.92%

10-yr Sr Notes, due 4/10/2025

$275million

4.27%

3.25%

5-yr Sub Notes, due 7/15/2024

$126million

3.85%

2.65%

5-yr Sub Notes, due 12/15/2020

$57 million

3.95%

3.90%

What is the firm's Kd?