Spreads markets in general

[MrBeauJangles]

I've been evaluating the platform and playing with backtester and noticing that most of the spreads have high win ratios for recent years ( > 2000) but going back further in time (< 2000) the losing years are more frequent even to the point of making a strategy non viable. So question is, why? Has something changed in markets generally? Is it a data issue? Is this a cause for alarm? Would like to get the groups thoughts on this. Thanks!

[Roman]

Hi, it can't be data issues, even the oldest data are verified and correct. Markets change over time, and what worked before, doesn't have to work now.