% Replacement

% Increase in Cost (∆C)

% Increase in Stability (∆S)

Increase Ratio ∆S/∆C

HW5

53

13

0.24

HW10

109

33

0.31

HW15

163

105

0.65

HW20

219

205

0.94

HW25

273

57

0.21