You are correct. Roughly 300% since 2008 over 12 years is an average of 25% per year. But, this does not take into account the compounding you mention. My returns are annualized using modified internal rate of return (XIRR function in excel). This takes into your starting balance, your ending balance, cash flow in and cash flow out. The number it gives you takes into account the compounding of your returns year over year.

Long answer longer; without doing the math, yes; my returns have probably come closer to the 8,000 you give.