Situation

I have the folowwing pandas timeseries data:

I need to take into account a case of resampling into bigger interval than a 5 years, for e.g. 10 years:

sample = data.set_index(pd.DatetimeIndex(data['date'])).drop('date', axis=1)['predicted1']
sample.resample('10Y').sum()

I get the following:

So resampling function groups data for the first year and separetely for other years.

Question

How to group all data to the 10 year interval? I want to get smth like this:

You can change the reference, closing and label in resample:

sample.resample('10Y', origin=sample.index.min(), closed='left', label='left').sum()

Output:

date
1999-12-31    1.547813
Freq: 10A-DEC, Name: predicted1, dtype: float64