You don't need us to tell you that a dollar just doesn't buy what it used to, but here's some actual proof about just how weak the greenback has recently been. With just over a week left to go in the month, the US Dollar Index is already down more than 1.7% on the year. That's a pretty big decline for a currency, but if you remember last year, the US Dollar Index kicked off 2017 with a decline of 2.6% in January, in what was its worst opening month to a year since 1987.

The chart below shows the US Dollar Index's historical returns for the month of January going back to 1968.As shown, the back to back 1%+ January declines has happened just three other times.The other three periods were 1972 – 1973, 1986 – 1987, and 2011 – 2012.