Updated October 2016
Here are some basic facts and figures about whooping cough from official sources. To get more detail or know my comments and interpretations just follow the indicated links.
In the 1940s, before whooping cough vaccine was available there were over 100,000 cases in the UK every year and the mortality rate was about 1%. After immunization became commonplace the numbers fell dramatically and instead of numbers being fairly steady year by year, the pattern changes to 4 yearly cycle of out breaks. It has got more like 5 yearly recently in the UK.
In the United States in 2014 there were 32,971 cases. In 2012 there were over 41,000 reported cases. This is the highest number for about 60 years. There were 18 reported deaths. In 1999 there were 7,288 cases. In 2000 there were 7,867. The CDC has an excellent website with up to date information and recommendations on the treatment and prevention of whooping cough (pertussis). USA CDC site.
In England and Wales about 5 deaths per year are recorded. In 2004 there were 504 notifications. In 2011 there were over 1000 notifications. The increase is probably due to increased awareness and the ability recently developed testing methods. In 2012 there were 9741 laboratory confirmed cases with 14 deaths. See news
It is my opinion, based on my research, that the actual number of cases that occur is at least 10 times the number reported.This is based on the fact that I have studied every case of whooping cough that I have detected in the community in which I work since 1977. This is in Keyworth, England, a community of 11,000. In England communities like this are often served by a single medical practice, making it possible to study such things accurately.