Over the past 5 years it's averaged only 4%/year.
30 Year U.S. Treasuries which have a duration nearly identical to the implied duration of this company's investments returned over 8%/year over that period from falling interest rates...
You are pleased with that miserable performance?
You should realize that per rational mathematical analysis the stock will most certainly decline in value if interest rates rise back to the Jan 2008 level, all else equal...