Government spending and revenue statistics
As you want data for OECD countries have a look at the OECD's Statistics portal. You will find the data in the "National Accounts" as section as well as in the "Public Sector, Taxation and Market Regulation" 

As an alternative or as a complement you can also have a look at the Eurostat database on Government Statistics. They do have data for Switzerland as well as for many OECD countries.

Finally, as you seem to be focussed on Switzerland, you can also try to find the data via the Federal Statistical Office. 

You can obtain time series by following the links in the "additional information" column.