HDB InfoWeb Appliation Status page does provide the application rate for last BTO project and SBF, breakdown by flat type. I compiled an Excel table with a summary of application rate for every BTO and SBF launch from 2010 to present and offer it for free download together with HTML pages.
Until October 2015 site redesign, the application rate for past BTO far back as Aug 2010 was still accessible via direct links (http://services2.hdb.gov.sg/webapp/BP13BTOENQWeb/BP13J011BTOAug10.jsp) although no longer visible in the Application Status page. I saved the pages so you can download HTML files from me.
An application rate 3.00 means that number of applications exceed 3 times flat supply, theoretically 1 of 3 people will be invited to select a flat. An application rate 1.00 does not always mean that everyone got a flat, because some flat types gets oversubscribed while others undersubscribed.
For example, the May 2013 BTO set a new record of low applicant rate: 1.07 overall, this does not mean that everyone got a home. The 4-room units got 4.3 in Hougang BTO while in Sembawang BTO the rate was 0.4 (60% flats remained unsold). Stupid idea to launch BTO in such bad location in the same time with SBF, obviously people went in SBF for better located flats.
In May 2015 for the first time HDB announced the launch date 1 week before the actual launch, the application rate being unusual high even after one day of sales, proving that HDB is still undersupply. Surprisingly, first time BTO exceeded SBF application rate.