Link to external data returning N/A

Hi there,
I am in the process of trying to create a spreadsheet that pulls data from yahoo finance to show exchange rates in real time.
The problem I am having is that the web page seems to load and then update itself a few 100ths of a second later leaving me with the initial figures in the table, many of which are N/A until the they’re updated.
Any suggestions on how I can get the data after it updates?

To give an idea this page is one that regularly returns N/A results.

Did you try setting a refresh rate when linking to the external data source?