Nothing to do with market fundementals and all to do with low liquidity currency markets and high amounts of repatriation for dollars/Yen.
The two best performing currencies in this market are the currencies which have had very low interest rates for (in the most part) a decade or so. So in reality spruiking this as a "sign" of a strong economy is completley flawed, as currency flow during a bull market (not bear) determines the strength of an economy.
If you really want proof look at a chart for the USD over the past 5 years and tell me where all their investment money was flowing.