With consumers feeling better about the economy, the amount of money borrowed has reached its highest level since the Great Recession.

Total consumer borrowing rose by $18.4 billion in May, the strongest gain since November's $25.1 billion increase, according to a recent report by the U.S. Federal Reserve.

While household income has grown over the past decade, it has failed to keep up with the increased cost of living over the same period.

To bridge the gap, more Americans rely on credit cards, one of the most expensive ways to borrow.