MebFaber provides a valuation Bollinger Band that could be used to adjust your domestic vs. global stock weightings. Look at the only times the US has been at or near the bottom 25% – the early 80s (start of greatest bull in US) and perhaps 2009. Now? Above the highest 25%! Right now, your allocation would be very heavy globally in markets that are broadly very cheap.
CAPE Bollinger Bands