You can easily sort the data / statistics by year, month or weeks. You do this under the page Health analytics. The basic setting is that the statistics show the month each time you log in. To change the month or go to a weekly or yearly view, do the following:
Click on the Health Analytics page.
Sort the range you want above the trend graph and press Refresh.
Check the desired month / week / year by pressing the dot in the graph linked to the occasion you want to check.