it's difficult to say from the info you're giving. It all depends on the the question you want to answer.
are you looking are somthing increasing or decreasing then you just plot the value against time, do a linear regression get the r-square value. the closer it is to 1, the better it fits a trend curve and the easier it is to say "parameter x increase with time" for example.
you cannot do T-test or anova by comparing a single point to another and so on!