From Matthew Graham at Mortgage News Daily: Mortgage Rates Match 2-Week Lows

Mortgage rates fell again today as several economic updates painted a slightly gloomier picture. In general, weaker economic data coincides with lower rates. First up were Retail Sales numbers, which moved into negative territory in February. Analysts expected a modest improvement. Later in the morning, several widely-followed sources of GDP tracking adjusted Q1 estimates significantly lower. For instance, the Federal Reserve Bank of Atlanta keeps a running tally of where GDP would come out today given the incoming data. Today's reading fell to 1.9% from 2.5% last week.
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The average borrower is likely to see the same interest rate at the top of the page (i.e. same NOTE rate) but with slightly lower upfront costs today (i.e. lower EFFECTIVE rate). With these gains, the average lender has inched down to the same rates seen on March 1st. [30YR FIXED - 4.5-4.625%]
emphasis added
Here is a table from Mortgage News Daily: