test time series?

Hello, I have a series of rates over a period of time (years) from
1975 to 1996, this is an example:
c(0, 0, 0, 0.92, 0.87, 0.695, 1.2175, 0.34, 0.3, 0.5475, 1.0575,
1.5325, 2.4375, 3.005, 2.635, 5.78, 2.7225, 3.9975, 2.6575, 3.6,
1.88, 1.9025)

What test can I do to see if any point (rate) or points are
significantly different from others? Or to highlight that there is
some outlier at a certain year? Visually looking at the data is fine,
but can it be backed up by a test? PS: the rates are X number of
successes out of N trials.
Thanks
.