How many people a year are diagnosed with asthma?

Difficult to know. The incidence of asthma (or new diagnosis) of asthma is tough number to actually know. The best guess would be based on the prevalence (number of people who have ever had asthma) and the total population. For children this would estimated to about 120, 000 each year. The CDC is a great source for this information www.Cdc.Gov. The number of people with asthma is on the rise.
Difficult to say... Some of the newer data have shown that 1 in 10 children and 1 in 12 people overall have asthma. Of course there are probably people out there with asthma who have not been diagnosed which would make those numbers higher.
Too Many. It is estimated that 1 in 12 people get asthma. And at this point in time, over 300 million people suffer with asthma worldwide. And its prevalence is estimated to double every decade. It is more prevalent in deveolped countries than undeveloped ones. However, that is now changing as third world countries become more industrialized and developed.